I got a helmet from him for free when I ordered my stormtrooper armor. Not thin at all and is actually very good quality/detail. In regards to your build, you should only have to trim the inside of the cap and back a bit then just fit the face plate to it.
Stripes: Straight across. About a pencil's width from the inner part of the helmet. There is a sticky for a TE2 Move Along build where TK4510 shows how he applies tube stripe decals.
ESB Holster: Goes on the right side I believe. Loops are required for EIB but not for 501st membership.
I haven't finished the ears and I know the mic tips aren't in, but I'm pretty happy with the result. Not sure if you can see the weathering very well.
It looks like it's on a mannequin, but it's on me!