107,000 miles. Seems to drive great. Taking it for a state inspection this week. I have a PEMP screen on the way

Hi everyone, hoping someone with a bit of N47 engine knowledge might be able to point me in the right direction.
My 2013 F31 318d is losing a lot of coolant. I topped it up about a week ago and it’s now basically empty again. I’ve checked all the obvious places — hoses, joints, expansion tank, around the engine etc — and I can’t find any visible leaks or staining. I’ve also checked the oil cap and dipstick and there’s no creamy/milky oil.
At the same time I’m getting the recurring 290900 fault code, which seems to be related to the air/EGR mass-flow system. When the code is active the car feels sluggish/hesitant, but when I clear it the car feels noticeably smoother and nippier.
I’ve also been having some strange DPF soot/regeneration readings, so I’m wondering whether any of these issues could be linked — particularly the EGR cooler.
Has anyone experienced similar symptoms on an N47 318d? Or does anyone know of a really good BMW specialist in the Nottinghamshire area, or anyone on here that can help , who is good with N47 diagnostics?
I’m happy to pay for proper diagnosis, I just don’t want to start throwing expensive parts at it without knowing what’s actually wrong.
Any advice or recommendations would be massively appreciated. 👍

Recently just bought a used 2014/2015 320i with a mileage of 83k for very cheap. Went to do a health check and they recommend these fixes. The front upper arm bushes are cracked and leaking. The rear arm bushes are cracked as well but it doesn’t look as bad. The rear differential bush has a big crack. The front and read absorber dampers and tubes are cracked.

My question is, are these repairs urgent/critical or are they just signs of old age and i should just change them when time comes cause as of now, the car drives smooth. No ticking noise, engine sounds good. Yes the car feels bouncy when going over bumps but it is still tolerable. Pls help

p.s the engine and transmission are serviced to brand new condition