Is it normal for a puppy to poop/pee on his own bed ?
PS: he is now 6 weeks old
He gets 3 meals/day plus treats.
He is putting on weight at a fantastic rate.
The pups I have experience with have usually been 7-8 weeks old when I got them. I never had one who was taken from his litter and mother at such a young age as 5 weeks, even now at 6, he's just a baby and you can't expect to seriously train him at such a young age.
I blocked off the kitchen with a baby gate, had a papered area for potty, and used that technique until my pups were trained. Training a dog takes a lot of time and hard work, but to have a well trained dog, who is not fearful of you and knows what you expect of him, makes a wonderful companion. For up to the first month of having a new pup, you really need to rearrange your schedule and make sure you're not neglecting the needs of the pup. In your case, he needs to bond with you, and have the comfort and security that he would have with his mother.
They depend on you for leadership, and to show them how to please you. They don't understand your words, but will respond nicely with positive training, calm and confident attitude. They sense when we're annoyed, nervous, upset, etc. The more secure he feels with you at home, the better he will respond to you.
Please be patient. Show him in a calm way what he can and can't chew on. Correct him gently, in the moment by taking away something he's chewing on and having a replacement in hand of something acceptable. I always kept tiny rawhide chew bones in my pocket at home, to have one on hand to correct chewing problems. When they drop it and walk away I pick it up for next lesson. Works like a charm. I never leave them alone with the rawhide, it can be a choke hazard especially for a young pup.
You can attach a small light-weight leash to his collar for a short amount of time during the day, under your supervision. Just dragging it around for a half hour at a time will get him used to it, if he starts to chew on it, calmly tell him no, you chew on this, while giving him something he can chew on.
With each passing week, your baby will be more mature and understand better what you want from him. Dogs are very loyal, they are very willing to please their masters, it's important that you guide them through the learning process with love and patience. Good luck, save the serious training for another couple of weeks when he's older.