Welcome to YT. Patience is the key. Like you already know, 7 weeks is awfully young to expect him to know what to do. You need to watch like a hawk and when you see the signs of him needing to pee or poop, pick him up immediately and place him on a pad. There are pads and sprays that will attract them to them.
I had several pads around just in case I needed to scoop mine up and place them on the pad. Once they learn where the pads are though, you will need to move them ever so slowly to get rid of them. Twice now Maggie still thinks that there is one by the laundry room door and it's been gone for about 2 months-but it was my fault, I hadn't replaced the one in their pen yet.
I also wouldn't take him out just yet as he probably hasn't had all his shots yet. I wouldn't chance him picking something up.
As far as food, you will need to switch him slowly as to not upset his tummy. You can wet dry food down and mush it up or water down some can food also. Definitely think about a good quality food.
You should always have water available for him no matter what, as you know he could dehyrate very quickly. What is his name? Would love to see pictures. He sounds like he's going to be a little spunky one.
Good luck with everything.