I am doing my own first restoration too!
For the panels, I dont really have advice. I have a more common pump so locally I have noticed a reasonable amount of parts available (certainly more than I expected!). That said, I think the answer depends on the factors in your case. For me, the pump is a personal thing as it was my great aunts. If I needed to replace anything due to rust, I would definitely have it repaired if possible before exploring reproduction options or finding spare parts on thr market. Its more the personal aspect of knowing it was all original to what my great aunt had used. Obviously, cost is irrelevant for the most part there in my case and depending on where your standing with yours and how bad the damage is, it may make more sense to replace. Thats my advice anyway.
Try searching the forum here for the colors, I was doing that for my Shell yellow and was blown away at how many options there were depending on where you are on the continent and when. I am sure you should find colour information on here somewhere.
The guts has been something I have noticed that is constantly debated. It was something that was hard for me to decide as well. Its definitrly a preference thing, so I wouldn't tell you one or the other. I would mention that my plan is to gut the pistons/pump, exchanger and some of the associated tubing but will keep everything else. Anything you dont decide to put back in, might be worth selling.
Anyway hope that helps. And good luck with the restoration. Sounds like your in fantastic shape already!