1998 ec250 question inside of engine RH side

[Rzez]

Hey all,

I've been tinkering with the ec250 i got a few months back changing the chain, suspension etc. All went well with thanks to you guys!

However I found that the kick starter was starting to kick back at me and damn rite scaring the b-jesus out of me!

Anyways decided the best idea was to start taking the engine RH side off to inspect if a novice could find anything slightly odd.

I'm yet to take the kick starter off and possibly replace a spring? (so I've read somewhere) but the following picture will show a bolt that rusted worst than i've ever seen on my dads old '66 cooper! Can't even see how to get it out. But before I go guns blazing I wanted to see if you guys
a) knew what that bit did
b) does it matter if it's rusted to buggery
c) any ideas on how to fix the kick starter?#
d) Does anything else look shoddy
e) Any idea on the seal thickness as the seal was completely deteriorated, apparently there is .1mm, .3mm or .5mm??
f) i've tried taking a picture of the case which appears to have a crack in it (where you insert the bolt through the whole. Could this be a massive problem? Or even the cause for the kick back? The 3 photos are of the same crack from different angles (not 3 different cracks)

Thanks for all your help guys. I'd ask my dad but he's pretty rubbish hence the '66 cooper is on blocks in the garage which is now next to my bike

Case crack;
http://i654.photobucket.com/albums/u...ki/image3.jpeg
http://i654.photobucket.com/albums/u...ki/image4.jpeg
http://i654.photobucket.com/albums/u...ki/image2.jpeg

rusted bolt;
http://i654.photobucket.com/albums/u...ki/image1.jpeg
http://i654.photobucket.com/albums/u...cki/image.jpeg