So much stuff!!!!

So, after deciding to completely strip my van down to barely a shell, I have ended up with loads of questions! You guys have been a great source of info and advice, thanks for all your help so far, you've saved me a ton of time and messing about.

The current questions are as follows:

1) The studs on my exhaust manifold were a total mess and when I removed the exhaust they stripped the thread totally. What is the best way to remove or replace them? I reckon they're probably rusted solid to the manifold. Could I cut them off and weld new stud to it?

2) Is it usual for a section of the floor to be cut away for the starter motor? and if not any ideas why mine might look like this:

3) After getting the engine up to speed and burning off the condensation from the engine the oil is now better. However, a tiny amount of liquid, about three drops worth, seeped out of the join between the brake servo and brake master cylinder. Would this be linked to getting the whole van up to speed/temp again, maybe condensation from the pipe running from the engine to servo? I eased the master cylinder away from the servo and it was ever so slightly grimy/rusty at the join which I cleaned out. The gasket seemed good, and no liquid has returned in the last few days. Could the master cylinder need an overhaul?

4) Was it normal on an auto to replace the metal gear selector plate with a plywood section, was this something to do with the dormobile conversion, or someone else's doing?

Cheers, Nick

So much stuff.It comes to us all