Yeah, that's what you should do. You can trade with anyone in the Union Room as long as both you and the other person have exchanged friend codes (you can both see your own and add others' FCs on the Pal Pad).
Well, yeah. Such a thread, a request for an evolution trade, should be posted in the Goldenrod Tunnel section. There aren't any trading limitations on direct trades, so you don't need to see a Shelmet first in order to obtain one in a trade.
I don't actually download any of the base files. I create the child style and edit them here on the site. You can't really go about creating a proper skin without the styling interface in the Admin CP unless you're some super expert.
Ohhh the size difference is staggeringly obvious. x_x Thank you for resizing it and repainting it for me. :3 When I said to not alter the characters, I just meant no creepy noticeable textures like Browsing deviantART I think it's supposed to look like he's covered in ice or something. Oh the horror! Or some sort of stitching texture. That's weird too.