A (F) means it failed to record the event. A (!) means their is not enough disc space to fully record that event to the disc.
You will get a F after a failed event and the ! before the event telling you to either change the disc or select a slower speed.
AFA powering up the machine the day of your event, I think(it's been a while) but I think that was only necessary if you used weekly or daily events. I don't think I needed to do that for one shot events.
AFA VCRs I know Canada Future Shops still had some last month, but I don't think any US retailers just sell VCRs only(those Canadians get everything)
Not sure if used would be OK but in my area anyway Pawn Shops and even places like the Goodwill stores always seem to have a large supply of older decent looking VCRs and their usually priced at a song, ~$10. If you went the used route and they didn't have a good return/exchange policy I'd bring a non critical tape with and plug it in at the store. Even without a TV if it looks like the counter is advancing and it's not eating or creasing your tape it's probably OK. The store might even have some tapes they'll let you use.