Good buy Gibbo, sounds like you got a great deal.
If you want more over steer/turn in get yourself a rear ARB (e.g. Whiteline), makes for some serious round about fun.
You're not going to get any meaningful power gains without forced induction, but the Gucci N/A solution is the RS2 inlet manifold with Cams. It's expensive though for ~200bhp and I'm not sure anyone makes the RS2 inlet anymore
Best cheap power mods would be 182 manifold, matched inlets, ktech induction kit, de-cat and a remap. But you'll still only be at ~185bhp
Would recommend warming it up properly as the F4R is quite oil sensitive, there are soft limiters in place until the oil is warm though so the risk of over revving is quite low.
I'd avoid Cooksport springs as I've read they corrode, H&R or Eibach are the way to go if you don't stick with the standard Cup springs.
Other things I'd look at are: Better exhaust mounts, suspension bushes all round, engine and gearbox mounts, high carbon front discs and DS2500 pads
I ran Dunlop Sport Maxx tyres for a while which were ok on the road, in 205/45/16, but I'd go with AD08R if I had another Clio for track days