"I'd recommend using the master shot method, which usually involves shooting the entire scene from start to finish in a long shot and then shooting close-ups and cut-aways.

I've found it to be the most efficient way to cover a scene."

Totally agree. Our first two features we followed this religiously and it saved us many times when it came time to edit. Always have something to cut away to (that wide master shot) when you need it. Without it, you may find yourself in a desperate situation that requires costly reshoots. Remember too, that one camera was the default in filmmaking for decades. There are many films shot one camera to learn from.

I've been happy with the Sony AVC/AAC renders for my 4K X-AVCS footage - downscaled to 1080p at 23.98. Haven't found a good solution for 4K renders though. Any suggestions?

I'll add my bit, which has been said many many times already. What camera you use is perhaps 5-10% of what will make your film a success or not. If you're low on funds, pick up a decent used Canon or Panasonic DSLR, or shoot on your iPhone. Acting, sound, story, lighting, story, acting, acting, story.... that's what matters. Get out and shoot ten short films on anything then worry about equipment.

A girl. A gun. A Car.
Fill in the blanks.