The 100% point is merely a design reference, a bit like the C of G datum. It rarely has any bearing on normal ops - RR Vipers were an exception with 100% being max T/O N1. Particularly as engines are uprated and flat rated for different installations the figures vary widely. Two examples I know personally are the Challengers with the GE CF34 engines with a max APR N1 of around 98% depending on model, and the Citation Ultra with JT15D engines with a typical cruise N1 of 104%. The same applies to N2.
EPR, on the other hand, has nothing to do with speeds - it is Engine Pressure Ratio. It comes from comparing intake and exhaust pressures, and so you will get different core and fan speeds for a given EPR with different atmospheric conditions.