Final Cut Pro - Editing multiple frame rates and sizes

I want to prepare three footage formats for editing together with FINAL CUT PRO 7, and need help so I don't come across big problems later...

Formats:
1. GoPro HD footage (1280 x 720) and some is shot at 60fps for slow mo
2. DVCPRO HD (1280 x 1080) shot at 29.97 fps (Transcoded originally in Final Cut from P2 Cards)
3. Canon 7D footage transcoded to Apple Pro Res LT (1920 x1080) using Mpeg Streamclip shot at 23.98 fps

Questions:
1. Do I need to convert the DVCPRO HD to Apple Prores? Better for alllll the footage to be one format? Which format?
2. Can I mix the aspect rations such as 1920 x 1080 and 1280 x 1080 etc?
3. Can I mix frame rates? And if so which frame rate should I set the FCP Sequence to? If I have both 23.98 and 29.97 do I need to make them the same before editing?
3. If I do need to covert everything to one frame size and rate what program should I use? And what is the best size and rate to convert everything to?
4. Is Mpeg Stream Clip a good program for any of this?
5. Should I make the clips interlaced or de-interlaced and should I set the timeline to progressive or not if I'm mixing both interlaced and progressive footage?

Thank you