all of your symptoms sound potentially minor to me. I agree, it is most likely the AOS, Air Oil Separator that needs to be replaced first. Then you should consider replacing your spark plugs and then draining your fuel and replacing with 91 Octane or better and adding some fuel injector cleaner and then run it for a while. I think your shifting issue is just sloppy cables, I don't know if the cables are adjustable or just have to be replaced. I haven't had to do that yet on mine. A lot of the parts on these cars are not cheap so you don't replace stuff for the fun of it unless you have a lot of disposable income.
