First I think you are doing very well in your planning...and you got a great price on it.... when you get it going and reliable you will love it... ( speaking as the owner of a 1980 manual trans )....
One item on nomenclature... ' spin on canister' ... a canister is basically a tube filter and will have a bottom which is part of the car.. you discard and replace the middle portion... a ' spin on' is like an oil filter on American cars... you unscrew the whole thing and put a new one on it....
When I get an old car I replace all the filters I can find... and I see no problem since this car is new to you and OLD.... in going ahead and checking/cleaning the screen or filter in the gas tank. Then you know what you bought.
If you just use 1. fuel tank filter 2. clear inline filter 3. spin on or canister filter (depending on what one has ) everyone will know what you are speaking about.
No special glue is required... rubber to metal is typically put on with ' yellow death' (the contact cement made by 3M) called ' super trim adhesive (?). But most any contact cement will work find if you follow the directions... which include cleanlyness and letting it ' tack ' before putting the two things together... both with a thin coat of the glue...
Do a search, lots of good specific info on cleaning and lubricating the sunroof....
Algae can really really be a problem.. so get a few tubes of Diesel Doctor or BioBar or whatever.... this has been discussed in threads also.... typically use a tube every six months unless you see black specs in your CLEAR inline filter... be sure when mail ordering that they send you CLEAR ones... opaque ones exist..you don't want them....
Most people get the factory shop manuals off Ebay I think.. at least I have on the bargains ... I did pay $200 when I got my first MB about 5 years ago for all the manuals except electrical ... which was 10% of the car price ($2000) and well worth it... but you may can get much better deals in Ebay auctions.... just may take longer to find them....
Yes,,, 99 percent chance the vacuum pump and brakes/shutting off are all one problem... and will clear up when you fix the vacuum pump.
The fluids are all discussed in threads.. lots of opinions there...