Omega Seamaster De Ville - any advice very welcome

Hi,
I recently purchased this watch, and I'm besotted with it!
I wondered if you had any information and observations about it. I bought it online from an American dealer with very good reviews. He described it as 17 jewels, 550 cal., 14K gold-filled, 31.78mm excluding the crown, with original dial and original crystal, which has been polished.
Some comments from me after a few months' use:
1 The crown has a letter 'W' or 'M' on it rather than the Omega symbol. So I guess this is a replacement? And do you know what the 'W' or 'M' stands for?
2 I read some information elsewhere that dated the watch perhaps between 1963 and 1968 - does that sound about right?
3 The automatic mechanism wasn't good enough to keep running (perhaps it's my sedentary existence) so I manually wind it every morning. I don't mind doing that though. I assume I'm not causing harm by doing this?
4 After the word 'Swiss Made' there is a letter 'T' - do you know what this stands for?
5 On the back it looks as if some eejit tried to get it open with a pen knife or similar, but I read somewhere that you actually remove the mechanism from the front? Not that I'd ever dream of attempting that.
6 The crystal feels kind of warm to the touch and more like plastic than glass in a tactile sense - but that's obviously not something you can tell from a picture, I guess!

I know very little about Omegas, but fell in love with them in a Bond film years ago and had wanted one for years.
I'd welcome any comments or observations you have about it. Don't be afraid to pull your punches. I got it for a good price and even if it turns out to be made in Taiwan, I've still got a watch I'm very fond of!
Thanks again, great to be here.
Neil

hi, you shouldn't wind it manually, it can damage self-winding part of movement. You should take it to your watchmaker to make for service.

3. If the watch has been serviced properly, it should be enough to keep the watch running if you're wearing it the whole day. So maybe you need to service it.

4. T stands for tritium, the radioactive material used on the hands and dial.

5. Yes, the movement is accessed by removing the crystal. Someone was really determined. Foolishly determined.

It's a well worn watch but it does look original with exception of the crown. The marks on the back could possibly be caused by corrosion. Get it serviced, throw away that awful bracelet, put it on a nice leather strap and enjoy.

Wow! Thank you so much for your advice and information. I've found out more from these answers than from the last three months of googling, and with the various reference numbers you suggest I can find out a lot more too. What a great forum, and I look forward to seeing some of the other pieces that come up here in the future.