Are the bushings worn down? Can I fix it with limited knowledge and tools?

Any issues with this model?

When I start my car, the esp light is not on but as I'm going down the street maybe 15/20 mins later, it pops on and stays on until I cut the car back off. This is happening everyday. Does it have anything to do with my brakes?

I got both lights on the green n yellow but the green goes off the yellow stays on n it air low

pushing the rear caliber piston in

Today I got an estimate from Audi for the exchange of the catalytic converter (driverside) of 4600,-, RepairPal estiamtes at max. 1193,- Can you name a mechanic who would the job for this money?

I need to add oil. What type do I use.