Jap. Vita owner speaking: FFX/X-2 Vita (2000 model) to be exact.
1) Yes, Vita is a region free console so it can be set to any language including English.
2) Yes, all you need is Eng. PSN account. You'll connect to the NA PSN store not the Jap PSN store. You'll need to make a JAP PSN account for that.
BTW most Jap. Vita atm should be the 2000 model so you dont need a mem. stick right away. The 2000 model has built in 1gb space which deactivates after you insert a mem. stick (which is stupid).