Going from high flow cats to OR X. Newb Sensor/tuning questions...

My car (just bought it -'88 5.0- and it's being shipped to me) currently has shorties going to high flow cats and a MAC catback.
I'm swapping out the cats and catback for a PYPES Off Road X and Pypes catback.

A few questions....

I'm new to Mustangs;
A) so how many O2 sensors do we have?
B)The Pypes X-pipe already has sensor bungs, but will I need extensions?
C)What's this about MIL eliminators that I keep reading about? Will I need these?
D)How do we go about tuning? In my ol' SS it was done with ls1edit or HPtuners thru the OBDII port. Fox Stangs have chips I guess? How do I get this sucker tuned?

Thanks in advanced. Sorry for the Newb questions.

Excellent.

Thanks.
The tuning question was for future mods (I didn't think an X-pipe swap would need tuning).