When people say Pheonix they often combine Scottsdale, Tempe, Glendale, Peoria, Mesa, and Gilbert. Because they are all part of the "valley of the sun"
Downtown Tempe is ASU, Tempe is a relatively small city ASU takes a big chunk of it, plenty of activities to do there, and if not, go drive to Scottsdale or Phoenix 5 minutes to 15 minutes away.
Depends on who you talk to 50,000 kids, if you go to W.P. Carey, Walter Cronkite they will generally be more academically involved.
I wouldn't think so, some of ASU colleges are ranked top 20. ex. W.P. Carey top 20 business school.
There is a lightrail that takes you from Tempe to Phoenix, so even if you do get bored in Tempe which you probably wont, you can always take the light rail and its FREE for ASU students