I believe I have the answer for you. My old 06 550i flashed all the codes you mentioned back in mid-2006. Turned out to be a common problem affecting a lot of E60s and a rare few E90s as well.
It's the steering angle sensor (SZL is the BMW code for the failed part). Once that fails, brake light turns yellow, DSC stops working, brake assist won't hold at a stop on a hill, and FTM stops working. Covered under warranty (hopefully you're still within 4yr/50k).
2011 E92 335i 6MT (Space Gray/Coral): M-Sport / Premium / Convenience / Navi / L7 / InvisiGuard / Dinan Exhaust & Pedals
2011 CR-Z EX 6MT, 2008 GSX-R600
RETIRED: 2008 Dinan M5 SMG, 2006 330i 6MT, 2006 Dinan 550i 6MT, 1992 Accord EX 5MT