Well there's me getting all down about it all and then MarkT comes along and cheers me up. I guess I look at it as a glass half full for now and see if the base matches up.
If not I'll worry about it then.
One question though, any experienced people has a crankcase welded or brazed with damage like mine, as shown above?

Going back to your post #3 re the kick start stop spining. I think its likely 'that' happened due to running backwards as is 'well split' & looks more damage than just a kick back or even a lot of kickbacks. Might be wrong though. We had 'that' happen on the YG5T farm bike 80cc which just had weak cases & had to replace the right side case under warranty from out of the crate in the end with factory modified cases after a few showed up broken.

I think the kickstart is to blame  

You can see that at some point the kick lever has gone forward -
The shaft stop (?) can be rotated all the way round, resulting in zero spring tension on the kick lever - The bit below
 

Maybe that happened and smacked the idler gear and bang..? (I'm new to all this so just guessing)
Anyway - New kick assembly on it's way as well....
 

Were you the one we were helping with the kick starter earlier? That's an old model, and it has been ungraded. You can get a new axle with that "dog" mounted. It is much beefier, but it requires a new push-out spring and engagement gear both are also beefier.
Forgive me if I'm repeating what you already know.

Yep, that was probably me. Got an upgraded one on its way with the new style cog and spring

Good deal! Didn't want someone going down the ebay highway and buying a discard from someone else's problem!