Its arrived and its in as poor condition as I'd expected. (On the plus side it was shooting strongly)

I have some questions and need some advice please.
In no particular order of importance;
the barrel pivot bolt is countersunk allen head on one side and a standard nut on the other, is that right?
The foresight element is held on place by a slotted brass screw. Again, is that right?
The piston seal is leather and doesn't appear to be giving a particularly good seal. What the best treatment for this or am i better off just buying a replacement?
Same with the breech seal.
The inner spring has snapped, so i reckon just replace both?
The grips are missing, i may have found some wood ones, but i would prefer plastic/bakelite.
The rear sight has gone, but I've heard an hw35 unit will fit.

By far the worst thing is the exterior finish! It has been painted at some point, but thats worn away too in the main, but the area where the grips should be looks to be smooth paint. Would that be right for the era? Also, how do i get a manufacter date?

So in summary I need:

Help and advice
HW35 rear sight
Plastic/Bakelite grips
Springs

Can you help?