hard on the peddle, id go a booster

does the stock master cylinder cope with the s13 brakes on the front?

A good upgrade is the s13 brakes for 120y strut. Just have to get the hub machined down a bit for the disk to slip over it. Fab or buy (approx $100) an adaptor bracket to fit the s13 calipers and that's it, a search on here will get you more detailed instruction

The best thing to do is Google this subject. Most of the returns will actually be from this forum.
Write down or copy all of the different options you read about into a MS Word file so you can refer back to it. It's easy to get side tracked while you're doing it.
There are hundreds of different options that people have been tried but it all gets a bit confusing after a while!
If you're going to change your rotors the likeliood is you will eed to change calipers as the standards won't be wide enough to accept the wider vented discs.
I can't give any advice of 120Y struts unfortunately as all my research has been into Stanza struts.
I'm not sure where you're located but Hoppers Stoppers here in Melbourne are very good at doing upgrades to standard struts.

ive got 120y struts on my ute atm, and im looking for some new brakes. i wanna replaces the pads and rotors, i was just wondering if there are any other rotors i could get that are better.. slotted rotors are also an option