Resource guarding (his food and toys) can be helped with training. I'm sure there are posts about this on the forum. If you can't find any Google it. Just make sure the source is a force free.
The other problem you have: peeing in the house. Is this dog neutered? If not, please do. The other thing you can do, is get him a pair of doggie diapers. If you cannot watch him, he is in his crate with a chew toy (Kong?) or confined. If he has to wear the diaper, he may not like the result of wearing a wet diaper, and catch on quickly. Just make sure you give him enough time to empty out his bladder! Males sometimes will pee 3-4 times before they are 'empty'. He has to earn the right to have freedom in the house. He can have 15-20 minutes freedom after he goes, then the diaper goes on IF he is wandering the house. If he is crated, then give him something to chew on. I have a neighbor that has a large wire crate for her little chihuahua, and she has pinned up some disposable pee pads around the crate, so if the dog has to go, the pee pads will catch it. Otherwise he goes out at least 4 times a day. I have trained my chihuahuas to go on pee pads (I use the washable human grade ones) as it is very hard to make them go outside when raining or snowing, etc. So much easier!