Jovan, yes you can mix/match jacket-trouser. and yes the size 40 will fit more relaxed (aka normal) than a 38, if that's your regular size.
Sounds great. My main concern is actually, "Will it still look good?" The chest and stomach match up on a 38
jacket I own which fits me just the way I want it so... I hope so! I really do want to take advantage of your generous offer. So as far as sleeves go, what do you want us to measure them from? Actual body or a well-fitting jacket? There's been some confusion over this between me and a certain online tailor, with allowances for shoulder padding, etc. Speaking of which, what's the construction like? Firm or soft? Thanks again.