I was away when the tourneys started up but want to join in now. 100
to 1 is still open but how many cames would I have to play at the
same time? 2 is OK, 10 ... maybe, 30 I wouldn't be able to handle.

Would it be an idea to say the number of concurrent games a tourney
will require on the info screen?

100 to 1 is in groups of 4 or 5 so 6 or 8 games (black and white
against each opponent).
If you progress to the next round there will be another 6 or 8 games.

Otto