Few questions regarding Vintage Seamaster

I recently got vintage automatic Seamaster. Not exactly sure about model, something similar to ~165 0003, 165 0005 or 166 0003, but it is cal. 552. Seem to have been polished and restored dial, new hands, which is fine by me - I consider movement to be the key even if case/dial is not exactly pure. I needed specifically 20 000 000 - 20 999 999 serial number for a year circa 1963. As you can guess for anniversary.

The price does not matter, may have overpaid but I had to get it in time and from specific year and this seemed to fit the bill - good condition, automatic, like black dial etc.

First question - does it need service? It supposedly has been fully serviced, but I have just tracked the time for a week and it seems to average -8s a day. Although I may not be entirely fair by leaving it on watch winder (perhaps not enough movement to fully wind vintage watch)? I was kind of expecting for it to run little bit fast? This isn't really a big deal, I just want to know if I need to take it to service or not.

Second question is probably dumb one, but this is first vintage Omega for me and I just wanted to make sure I understand it correctly. So it seems crown only turns clockwise and watch can only be adjusted backwards. Is that right or am I missing something? I know that it is correct to wind it clockwise, but I was expecting to be able to adjust the time normally. If I turn the crown CCW, then it just unscrews. Is that normal?

Few pictures for the end (again I believe this is replacement dial, with dauphine hands which I am not sure is correct for the model):

Thanks for confirming.

Seller claims to be watchmaker himself and said he serviced the watch before selling. So I doubt I could get any more information there. I assume it needs to be serviced then.

Yes the crown surprised me, I thought drop of treadlocker would fix it as well, but didn't want to make assumptions and damage something.