I've got an older house with old 2 conductor wiring in place that I'm
working on upgrading. The rooms next on the rewiring list have a
combination of overhead and underfloor supplied outlets and I'd like
them on the same breakers if possible, so I have some questions to put
to the group to add in to my consideration:

1) Should I run my under-house wiring in conduit or is just the plain
Romex good enough? I'm currently leaning toward running it through
conduit, to ease future replacement/repair if it's ever needed. I'm
thinking about the thinwall 3/4" galvanized pipe that I can bend with a
regular pipe bender. I'm anticipating only 1 12/2 wire per pipe.

2) Since my rooms have a mix of under floor and overhead supplied
outlets, can I wire both sets up to the same AFCI breaker in my central
breaker box? Some of the other breakers I've installed have the screw
down plate with 2 bumps on it (like this: n_n (where the "n" represents
the bump and the screw penetrates through the "_")). I've done searches
on the archives here, but I saw many mixed responses, so I wasn't sure
what the current rules allowed, and I haven't installed an AFCI
breaker, so I'm hoping someone who has can answer that question (BTW my
breaker box is Square D).

Thanks for any responses!

-Nathan