Nice alloys mate, remind me of something though - do BMW do sport alloys like them?
They're tasty though
For lowering, you will need to get new springs, I'd personally recommend the Eibach's - cheap enough and good enough to have been selected by TTE to sell on as their own.
Less than £200 and transform the ride. I went from standard suspension to coilovers and then to the Eibach's and the comfort was great after the swap :)
As for the kits, try sites like Prolex, TDi, Altezza Sports and Prestige, or if you want a definitive list, check out www.takakaira.com - they've got nearly everything you can possibly get for the IS!