The carb (assuming it's a Pierburg, and assuming the 2e3 works in pretty much the same was as the 1b3..)
Automatic choke on all the time: Adjust the choke by unscrewing the three phillips screws holding the choke housing in place and rotating the housing. Or preferably, get a manual conversion kit or a weber replacement carb..
Not ticking over / running rough: Most likely to be the mixture badly adjusted in my experience.. the mixture screw is a bloody fiddley little thing and hard to find.. look for a small screw head poking out of the front of the carb somewhere, probably through a hole in a metal cover if it's anything like mine was. Turn clockwise to richen the mixture, turn anticlockwise to weaken it. If you take a look at one of your spark plugs you'll know whether it's too rich or too lean, if it's running rich the plug will be covered in black soot, if it's running too lean it'll be grey/white. Brownish grey is what you're aiming for if it's well set up

I will say this though, the carbs fitted to these things are right buggers.. weber and pierburg alike.. although at least with the webers you don't have to worry about adjusting the auto choke as well..
As for the rest.. I'm afraid I'm not very helpful. Arch rolling, either leave it to a body shop to get it done properly, or do it like I've just done, with a hacksaw, a file, a can of rust proofer and a lot of patience..
The suspension.. I can't really advise how to stop the springs falling off, but I will say that holding your suspension together with cable ties is a bodge that even I wouldn't try, and that's really saying something

I'd suggest getting down to a scrapyard and picking up a pair of rear struts to tide you over until you can get it lowered properly, shouldn't cost you more than £15 or so if your scrappy isn't stupidly expensive..
Door cards, haven't done it yet so I can't really help there.
Cleaning engine bay:
* Wash the loose stuff off with a hose and a brush
* Soak the thicker stuff with petrol or a commercial degreasant (petrol works every bit as well and is much cheaper)
* Scrub it away with a hard bristled brush.. a washing up brush tends to do the job nicely, and a hard toothbrush is good for the fiddley bits
* Where the paint is stained by the grease, use meths to take the grease off (wash off with detergent before it eats your paintwork away though..), then t-cut and polish the paintwork.