Sounds good, you got a really good deal on it if it was in good shape. But over time, with all those upgrades, i still think it would have been better to start with an m3. I suppose you can spend $8-12k if you do all the work yourself......but in the end, if you ever decide to sell it you won't get back nearly as much money as if it was an m3.
Don't forget you will need the sub-frame re-enforcement plates which already come on an m3, or you'll cause damage to yours.
I wouldn't bother with the s52 swap unless there is something wrong with your engine. M3 Cams, m50 mani, intake, tune and your at M3 power.
If your on a budget, i think there are some used Bilstein coil-overs in the for sale section. If you want to spend a little more, check out BC Racing ones, Jay at Stance Factory can hook you up. You can order any spring rate you want and the shocks will be valved correctly, and they also come with camber plates and rsm, which i wish my FK kit came with.