The liners you'll probably go through quickly in the beginning, then you'll start needing to change them less often. Babies are messy, haha. Currently I change Archimedes' once a week (he's a little over 6 months) but when he was a baby it was more like every other day.
The food I always recommend is Chicken Soup for the Cat Lover's Soul - but, unfortunately, there's a major (voluntary, precautionary) recall going on with the Chicken Soup brand of pet foods right now, so it's going to be scarce in a lot of areas for the time being. So, that being said, Natural Balance GP&D has been high on my list for a while. I got a small sample a few months back, which Archimedes enjoyed, but I never actually added that to his mix. A lot of people recommend that one, though, as well as Innova reduced fat. For the Blue Buffalo, I don't know off the top of my head which versions of it are the best choice, but if I remember correctly, it's the Blue Buffalo Wilderness that's too high in fat. It's a good idea to have a mix of at least two - this recall being a prime example of why - though you'll want to introduce one gradually first and get him transitioned fully to that before adding a second one. Basically any of the ones you listed would be a good choice, beyond that it's personal preference - though if you're planning to use two, the Natural Balance might be a good choice for one of them just because it isn't chicken-based.
I make all my hedgie bags myself. If you have basic know-how with a sewing machine, they're really easy to make, and it's a lot cheaper compared to buying them from etsy. There's a how-to guide for those in the housing/accessories area of the forum (under DIY stuff). There are also some forum members who sell them.
And belatedly, welcome to the forum! We love it when new owners do so much research and preparation in advance.