W126 valve seals/ballstuds/rocker arms

[Q]

!985 380SE

I am a capable DIYer. Am I getting over my head (no pun intended) with a project like this? Seems pretty straight forward, but I'm sure I'm missing an important detail or two.

Here is what I assume:
remove obstructions to valve covers
remove valve covers
rotate engine so lobe on one cylinder is straight up
use valve spring compressor to allow removal of rocker arm
remove ballstud
do same for other valve
place cylinder at TDC
apply air pressure to spark plug hole (how much pressure?)
break keepers free
replace seals
return springs/keepers
new ballstuds
new rocker arms
new oiler fittings
new valve cover gasket

Any tips, tricks, useful information are GREATLY appreciated!

Main questions are:
1) is there any adjustment/measurement necessary for ballstud replacement?
2) is cam wear a possible issue at 115k miles?
3) will cam/rocker arm wear be obvious?
4) what is best way to free keepers?
5) do I need to lock the flywheel when applying air pressure?
6) shoud I replace valve springs?
7) how difficult would it be to add Euro cams at this point?

Pardon my lengthy questions. I am trying to piece this all together from what I have read on the forum. I like to be fully confident that I have all parts and working knowledge before starting. I have the manual, but haven't studied it yet.