As long as you get TUV approved springs, i.e most manufacturers you wont get spring dislocation. Dampers are a good idea, but it depends on how you like your ride, konis can be a little hard until they warm up, but the improvement in handling is worth twice the grief!!
You can put 205 width tyres on, with little problems, but i,ve got 225/45/17's they took a bit of arch work and the lack of windscreen washers to fit (bottle scrubs on front tyre!!!)
Best handling? Eibach springs + koni dampers
Comfort? H&R springs standard dampers.
You need to lower the 145 cos it has a dodgy lift off oversteer built in. It will catch you out one day, trust me.