First Time Using Premiere and Proxies and 4k

This is my first time using Adobe forums, so I hope I am doing this right.

I have just started to ingest footage for a feature doc. This is my second feature. I edited my first feature doc on FCP 7 (gasp!). It was all c100 1080p footage. I just transcoded everything to ProRes and went to town.

Now I am using Premiere for the first time and I have both c100 AVCHD 1080p and c200 AVCHD UHD (3840 X 2160) footage. I'm trying to use proxies.

So I set up a project in premiere and set up my ingest settings for 720p ProRes 422. I have a 2014 PowerMac.

1. Is that the right codec to use? (720p ProRes 422)

2. The final export will be 1080p. Is that what my timeline sequence should be? (Or should it be 720 to match my proxies?)

3. I want to be able to scale up/zoom in on the UHD footage to make medium shots out of wide shots. Do I just reframe in the timeline as usual and when I export the quality will be maintained? When I look at the UHD footage in the timeline, it is too large to fit. How do I fix this?

4. Will the proxy files appear in my project? If so, do I drop those into the timeline. Or are the proxies just invisibly attach to my high res files, and I drop the original file into the timeline and premiere know to edit in proxies? Or I toggle between the high res and the proxies as I'm editing? When I toggle I don't see a difference? Is it too late to add a watermark?

5. How do I synch the two cameras? The c200 footage had 4 channels of audio and the c100 has 2.

6. Finally, how do you organize? In FCP I used to rename the clips in the hard drive after I transcoded them before I put them into the NLE. I know NOT to do that in Premiere. But now I have hundreds of clips with nothing but confusing numbers. Do I just make a bunch of bins? Or do I make a bunch of sequences?

I started ingesting the footage from my hard drive. Media Encoder worked all night and then ran out of "application memory". I looked through the files, figured out what had not been completed, restarted the computer and started ingesting the incomplete footage again. That's running now.

I hope my 2014 Power Mac and LaCie D2 Thunderbolt 2, USB 3.0 7200RPM 8TB Desktop external Hard Drive STEX8000100 drive are enough. I'm starting with 500gb of footage and that's just the first shoot. Should I get a bigger/faster drive?

I know this is a lot of questions, just pointing me to your favorite sources or links for info would be much appreciated.

Thank you for your time and energy.

-Laura VanZee Taylor