BMW has admitted to their windows being able to scratch tint. But if your car looks fine, you're okay. I have tint without issues. As for stickers, you should be fine. Plenty of people have their e90post stickers on their car without problems.
2007 E90 335xi - "Sera"
aFe Stage 2 DCI | AE Performance Exhaust | COBB Accessport | HPB Interior LED Kit | M6 Wheels | ER Charge Pipe | MTEC LED Angel Eyes | Helix Intercooler