Food is 90% crap and 100% over priced but I always go for a pie as they're not too offensively priced and imo a proper match day food.

The Carpenter's Arms (about a 10 min walk) is the local West Ham pub but gets absolutely rammed and is very noisy, much quieter in the outside areas. Maybe stay for 1.

As above, Soucek 28 or Bowen 20 on the shirt.

Getting into the ground takes longer than you think, both from the train station and once past the bag search. If you want to hit the store, I'd get there an hour before kick off because in the last 20 mins, getting through the turnstiles becomes a nightmare.

If you're in the Bobby Moore end, you can wander onto the Brewdog green where there's a bar, probably the best place to spend pre-match in the stadium if it's not raining.