1.I am not familiar with UK, for US schools, 660 is a average level for schools beyond top 15-30.
2.no matter which one you require, ETS will send all the last 3 scores (if applicable, in you case, the two scores if you require on the test day, or after the second score is marked.), with the same charge, US$25/school.
3. no idea.
as I know, some bschools look at the gmat scores separately. So they will take you higher scores in the three section: math, verbal, and awa. Don't worry, just check them out in their website.