There were some Mandalorian's who didn't wear helmets. Master Jaing who's skull you have on your chest was one as well as an early Mirta Gev suit. In my opinion, the helmet makes the armor.
Sarim pretty much has a good answers for everything =) (Good job Sarim!)
I would say that if you want to stand out...make things work. Now, I wouldn't make your flamethrower work as we don't wanna set kids on fire. However having working chest displays, moving RF stalks, lighted gauntlets, and other do-hikies is what attracts the crowds. Trust me, people love to see your armor "work". =D
For the vinyl helmet ring...I don't know of many people who do that. Mainly because the helmets are already so dang hot. That would just make it worse! Most people use Baklavas over their head...and even those are pretty darn hot, I don't normally use mine because luckily I have a short neck and not so big melon.
For your T-Visor, you can always grab a welder's mask and cut one out of that. They arn't very expensive at all and you should be able to get one at most hardware supply stores.
What you have done already looks good! If you plan on upgrading, just upgrade in small steps =)
