I'm not an authority, but for the folks who are, you may want to take pics at multiple angles, and maybe some in daylight. Also, check out the Star Wars Helmet site.
Well I actually haven't got the helmet yet these are pics from the ebay auction. As soon as I get the helmet (which should be tomorrow) I will get some more pics.
In The Don Post deluxe, the T-Visor is kind of flush to the outer surface...similar to the one in your photo. Thats likely what you have, unless the old cheap Don Posts are selling for $150 these days...which would surprise me.
paint job kind of reminds me of something that used to be on ebay all the time years ago, possibly something from Starfortress like a recast of the DP statue. My eye isn't that good though, someone else can probably spot the tells better.
I don't know what the helmet is made of and I most likely won't find out. The person who I bought it from hasn't even shipped it yet. The tracking number I got was for a grill cover my grandparents ordered and they forgot about it. I am going to ask the guy for my money back. It is rediculous I bought the helmet 2 weeks ago and he hasn't even shipped.
The visor definitely has some sort of film over it ,you can see small specks poking out from behind,though most likely you would be replacing it anyway.
It looks like a vinyl Don Post '96. It's definitely not a '95 because the visor sits too shallow. The dent and the ears are also a giveaway. As for the RF...well that depends on which version of helmet you are going to do. ESB and RotJ had different types.