The obvious thing is to get bigger brake discs and pads. This can get expensive though so you might be better off just getting some good quality pads.
Are the brakes in good condition? Rough up the disk surface with some wire wool and that might help a bit.
Power wise there is not a lot you can get from a 1300cc. It is a lot of work for very little gain. You could try a fast road camshaft profile, head flowing and porting but you will only see 10bhp or so more for this on that engine.
most cars from 1999 onwards can be remapped however it really is a specialist job, you can get the software and cables off the internet but youll struggle to find any generic maps installed as the performance companies spend thousands developing their maps to get the best from the ECU without causing damage to the engine itself