Xterra wetsuits have arrived

It should be fairly tight but able to breath and move around without a problem.  It will stretch out.  A wetsuit is like a sponge.  Once you get some water on the wetsuit you will notice it to stretch much more.  Dropping 40 lbs could mean a whole size change.  and I'm not sure the comparison between full and sleevless.

Good luck and keep us updated with your success.

tighter the fit, warmer the suit

That is true.  Also these wetsuits should be a LITTTLE different then surfing suits.  I had a surfing suit and mobility in those thing are much harder. 

I wouldn't worry about the sizing after you lose the weight. I'm 6'2" (disproportionately long torso) and 225 pounds. My XXL sleeveless fits perfectly.

BE CAREFUL.  I got an xterra less than a year ago..nice sale but now I need a new one.  The one I got last year ripped the second time I put it on.  after much hemming and hawing they replaced it.  I have had multiple small rips in the replacement.  I went to put it on yesterday...had it inside out and was pulling it on FROM THE INSIDE (yes I know how to put on a wetsuit no I do not have long fingernails yes my previous wetsuit was rip free with 4 years of use) and I put my entire hand thru it.  I'm SOOOO not happy.  I know of no one with an xterra who has not had problems with rips.  Cheep is good but if you have to replace it in less than a year not so much

Thanks for the comment.

To answer the OP's fourth question: significantly hotter.

I ordered a Vortex 3 fullsuit, and it had its first taste o' the brine last Sunday. The only other wetsuit I've used is a sleeveless, and I notice a big difference in warmth. Not to the point where it was uncomfortable in the water (quite the contrary, in fact), but it was definitely warmer. Ocean temps out here are usually in the 60's during spring/summer, FWIW.