1) Is .999 Fine a must have for you? Be it gold, silver, platinum, palladium, how do you feel about alloys (sterling, white gold, purple gold, 90/10 Plat/Irid)?
Personally, I rarely buy metal that isn't .9999 anymore unless I really like the coin, then I'd buy a .999.
2) Are standard weights a must for you? 1 troy ounce vs 1.3 troy oz, 17.983g, etc?
I tend to like my collection to all fit nicely together, so uniform capsules or storage tubes is a must for me.
3) US 1 Oz Gold Eagle question: The 1 Oz US Gold eagle weighs 1.09 Oz because its 22K gold instead of 24K. Its marked as containing 1 troy ounce of fine gold, though the metal is not fine gold, its 22/24 % gold.
I no longer buy US gold eagles because of this. I much prefer the purity and finish of Canadian coins.
4) Under marking: Marking is a minimum standard, would a piece marked 1 troy ounce gold that weighs 32.3 grams bother you? Same question with regards to purity, if I used 98% silver and marked it as 95% would you have any problem with that as long as you are getting more than promised?
It would bother me if it were marked something that it wasn't. That should not ever happen. However, if it were marked "~1 troy ounce" it wouldn't bother me at all, because I'd feel like it was meant to be as close as possible to 1oz but maybe the maker didn't have the necessary equipment to do it perfectly and was still trying to be completely honest.
All that being said, if you made something unique and it was meant to be a show piece and not something stored in a collection, I think 90% purity would be a better choice due to being able to better maintain it's shine over time. Just my 0.00000002 BTC.
(edit)This is unacceptable, even if I am getting 98% metal while paying for 95%
I should clarify that I don't feel this way about purity. If something is marked 95% silver, it should contain 95% silver. The other 5% could be more silver, as that wasn't specified. It is only if you claim something is there that isn't in your coin that it becomes a problem.