Questions from a former MythTV user

Hi all, first post here.

I just got a Roamio OTA and have been enjoying it thus far. I've been using MythTV for about 6 years now and had some questions.

There's countless threads on power/sleep, etc, so I get that we shouldn't turn TiVo off (just like MyhtTV) but what "screen' should I leave it on? With myth I would always exit so the tuner isn't in use.

And if I should just leave it on a channel, what happens if it needs to record using all tuners?

Finally, do you guys typically delete things after watching them? Or just let them auto-expire?

Thanks in advance!