I am going to replace the no.1 stud and no.8 stud on exhaust manifold should i replace the gasket and the rest of the studs and nuts at the same time?
I recently blanked off the EGR and managed to break the nipple on the air pipe and the green check valve above,

I have temp repaired with silicone tube and check valve from the pet shop and drilled hole in airpipe stuck a nibble into it and connected to silicone tube. am i doing damage driving my bongo? Is the air from the air pipe pushing into the switch or pulling out of the switch, ie which direction should the arrow be pointing?
The garage has put in so much oil it reads higher than maximum should i be trying to take some out to bring in down?