I first learnt how to do bound buttonholes when I was at school, and thoroughly enjoyed doing these. Back then we had the heavy black Singers, and even if I was using an electric, hand crank or the treadle I was taught to go slow and count the actual stitches, so that each side had the same amount of stitches and the two ends also had the same amount stitches. I do think that bound buttonholes and lovely buttons, even covered buttons do add something to a garment, it sort of lifts the garment into something rather different.
Why not try stitching out some sample buttonholes on some of your fabric scraps and see how you get on.
With regards to having a pleat in the lining, the answer is yes, it will just make the jacket that little bit more comfortable to wear, if the lining didn't have this pleat, then you might feel you are a little restricted with your arm movements and you do not want to suddenly hear a split as the fabric gives way under strain.