Hi everyone, new to the forum and new to training.
A little who-am-i and what-am-i-doing-here:

I live in northern Norway, currently working in I.T., I've had my dog for close to 7 years, he's the only dog I've owned after childhood.
I'm not a professional trainer, but a hobbyist with a newly discovered strong passion for training.

I own a 6 year old male Perro de Presa Canario named Dexter.
At the time i got him, I'd just left the army and searched far and wide until i found a good kennel in Sweden, and promptly went to purchase a puppy I'd fallen for. Sadly, this puppy died soon after birth, but I met Dexter and he was just absolutely crazy! Noone else wanted him of all the other prospective buyers, because he was so active, and he was smaller than the breeds optimal size.
Somehow i fell for this pants-biting jumping little furball, and took him home.
I went to all the forums (local), and searched up all the dog-training info I could.
In hindsight, I ended up with all the wrong info.

Living in northern Norway, unfortunately I didn't have access to quality information about training dogs. Up north, we have no IPO/Ring/protection trainers or circles, and the trainers I found were very old-school in their methods (in hindsight).
I didn't train Dexter to bite, never playing tug or anything bite related. I was told the old tale about how dogs will start biting people if you allow bite-play.
We did almost purely escape/avoidance training, with food rewards on top of that. All this in the belief that this was how to train dogs, on the advice of what passed for professional trainers in my neck of the woods.

Present day: He's a really sweet, caring and energetic dog, but he's very gentle and careful in his behaviour. Even when aroused and engaged, he'll be careful about his movement and such.
He's very youthful for his age, both physically and mentally, and he learns quickly.

Recently a friend introduced me to Michael Ellis, lent me one of the DVD's, and now I'm hooked on dog-training.
4 weeks into training Dexter, he'sa different animal entirely, and I'm a completely different trainer/owner.
It should be said that I have more to learn than the dog, and i recognize this.
I've gotten almost all of the Ellis DVD's, and i probably watch 2-3 a day repeatedly. I listen to them in the background while at work, and i revisit any relevant topic before a training session.
I train the dog as much as i dare without tiring him out, usually mutlible short sessions a day ranging from 3-15 minutes, and several longer 30min+ sessions a week.

His food motivation is insane, and he learns quickly and is quite rapidly turning active, where he was reactive before.
He's gotten into the biting/tugging again, I just started as I would with a puppy to ease him into it, now he's on tugs and pillows.

All in all, the training is going great, especially considering how new to this method I am, and that Dexter has previously learned behaviours thats a little at odds with the new training.

I do, however, have a few problems that I'd like some educated tips on how to solve.

Bite-work:
He's somewhat hesitant on the strike while playing tug, when he clamps down and tugs it's all good, but after release he can wait up to 3-5 seconds before he strikes. I also struggle to get him to WANT to bring the tug back to me.

Spatial Pressure: He doesn't move at all. I've stayed at it and rewarded half-steps backwards, but more often than not he doesn't move until I'm physically pushing (hard too), and I'm wondering if I should try to combine leash pressure into it.
This is likely because I've trained the dog to tolerate children, and I've probably overdone it. My godchildren can literally climb over him and he doesn't care.

Food handling:
This dog has a gigantic mouth, and he's probably as highly motivated by food as it's possible to be (which makes most training really easy). He ends up getting my hand a lot (not hard), and it's getting hard to keep the food in my hand when covered in slobber :P
This makes it harded to get him take the food with energy. Intensity, yes, but he wont chomp on the food itself, which makes it fall onto the floor more than I'd like.

Engagement:
As he's so highly motivated by food, I get really intense engagement from him, but somehow this doesn't bring the arousal I expected. He's eager as heck, but he's still a little calmer and more collected than seems natural for that level of engagement.

Any and all tips are more than welcome, I am new at this and I know it.

I'm watching these DVD's for my current training:
The Power of Training Dogs with Food
The Power of Playing Tug with Your Dog
Advanced Concepts in Motivation

I have more DVD's but I want to get all the basics down before we move to more advanced behaviours.

The Power of Playing Tug with your Dog and the Advanced Concepts in Motivation are both excellent for what your looking for.

At the same time the Presa isn't noted for high arousal in prey work.

They are more of a defensive breed as in "bring it on but If I have to get off my ass to chase you forget it".

My brother's Presa loves a game of tug but it doesn't compare to when the dog lights up on anyone near the car, yard, etc.

Ellis is top of the heap as far as I'm concerned.

My brother's Presa was 3 yr old when he got him and brother was told NOBODY could trim this dog's nails without hog tying him.

Once tried both the groomers and the vet said no way without sedating the dog.

We worked with markers and in a mater of a few weeks the dog now lays on his side and snoozes while his nails are being clipped.

Yeah I've gotten a lot of "you can't do that with a Presa", so I think of breed-related advice with healthy scepticism.
I'm still concerned with working against his genetics, and you might be on to something on the low arousal prey drive, he's never been into chasing other animals.

I'm only 4 weeks into training, and I try to simulate working with a puppy (progression-wise) as much as makes sense. I'll probably get a better read on what he will and won't be suited for during the training forward.

I'm also looking into some IPO clubs in Norway, so I can take some classes in decoy and handler work.
In Norway we aren't allowed to do bite-work on sleeves and suits unless you're certified (I think this is a great idea), so that's a must going forward!

Have you tried a flirt pole?

The quicker movement can often up the dogs activity level compared to just playing tug.

Tug work actually requires a bit of though when working a dog.

If your movement isn't fast enough the dog looses interest.

If you try and work the dog to long the dog looses interest.

You need to make the dog miss the tug more then you let it get the tug.

You don't want to make it to easy such as reaching in to let the dog get the tug.

One trainer (Flinks) uses the term "The rabbit doesn't jump into the dog's mouth" meaning the dog is stimulated by the chase.

I believe the object becomes secondary to the chase.

Make sure you're handling your food with no fingers in the way and he will eventually learn to get on in there to grab it fast. The way Ellis teaches is great but I always drop the food all the way into my cupped fingers so they don't have to go digging for it. A dog that's been taught not to bite fingers might be uncomfortable with pushing all the way in to grab it.

I keep a washcloth tucked in my belt when I'm training a drooly dog.

You can start spatial pressure with you pushing him hard it just takes longer to get to the point you see in the DVDs.

Thanks for the tips, much appreciated

I'll continue training, and see what results i get.
The food I've been using have been chopped up hotdogs, I found out that drying them a little bit makes them a lot easier to handle.