B&W film developing questions

Ok, I just developed my first 3 rolls of film at home, and except for a 
little bit of dust on the last roll the results are excellent.  I'll 
s****adically be developing more over the next couple of months.

I'm using Rodinal, Arista's indicator stop bath, Arista's Universal 
non-hardening fixer, and Kentflo.

Questions:

1.  The Rodinal says undiluted it will last 6 months.  Can I be safe to 
assume it will last that long?

Also, with the Rodinal I've been developing only one roll per mix 
because I'm new at this.  With Accufine, the previous developer I used, 
I would do a couple of rolls in one canister before dumping back into my 
storage container and repleni****ng.  And after 3 months at the same 
developing time my negs were a little light.

Can I develop more than one roll of film in my Rodinal?

2.  The stop is the least of my worries, right?  It should be ok for a 
couple dozen rolls over the next couple of months?

3.  What's the expected longevity of the fixer?

Thanks,
Greg