stoopid connectors and odd looking ribbon looms yes, but everything electrical still works on my 92' Sunny winter daily - bet many other manufactures of the same era cant boast the same ie your astras, rover 200's escorts and 309's..........
What's the battery voltage showing once the engine is running? Anything less than 13.5 means the alternator isn't doing it thing sadly. Chances are if the alternator has been weak for a while, it will have been asking the battery to do too much causing it to also fail.
hit the ground running haha
for me on any car IF you go aftermarket wheels, you need to go with at least an inch bigger that what is commonly seen ie the 18' RAYS.