Hey guys, I cant seem to find any proper info on the web (surprise right?)

First question - I want to change my spark plus, im at about 83k and pretty sure their original, When i remove the intake manifold to access the other side, do i need to replace the gasket?

Second question - I also need to change my Rear sway bar bushings/links, Cant seem to figure out what diameter my bar is though? any suggestions for replacements? I only found that maybe my car is a 22mm bar? but some suggest 24mm. so im unsure.

any help would be great, Thanks in advance!!