Hall sat for a bunch of games so he definitely needed to see regular pitching. Obviously if he keeps slumping they won't call him up immediately, but I am guessing if he has a good weekend series he'll be called up when they get back.
If Castellanos is still out they should put him on the IL. After this series and another off day he would be eligible at some point next week too. Of course we'd rather have a better left-handed hitter who can play RF for Vierling against RHP and we don't really have that at AAA unfortunately.
As for the playoff rosters, I think we go with one less pitcher and one more hitter for all series. We just don't need 5 starters and if a starter can't relieve (Thor) then they should not be on the roster. I suppose they could make Suarez the relief swing starter in the playoffs, but he is kind of the number 3 starter now even with Wheeler back. I rank them Wheeler/Nola, Suarez, Gibson, then Thor at the moment.