I'm fine with 10. With a bigger window you maybe have more hard decisions on the way, which is (I think) more entertaining. (Also 10 is a nice number)
As for the Top 100(/1000) Play-offs: Since this strips already survived one round, I would maybe consider a different voting approach for them (10 is not the greatest number for that :/).
Maybe something like first voting on two 5-strip-batches (organized in a determined fashion, so maybe first batch 101-150, second 151-200, or odd decade batch vs. even decade - I would vote on both batches in the same week, but you could add a week for separate voting), first advances to final (or maybe even the two bests advance to half-finals, adding an additional voting-round, with first winner of one batch against second of the other - maybe only adding half-finals for the Top 1000, if we reach them)
For the update schedule: think 1 week is fine (makes updating easier, since you can just update every <favourite weekday>), other option would be to couple this to the comic-update (like the Favourite Character Tournament), but I would prefer the fixed time.