good for you, peeves! the bigger room should serve you longer.
offhand, my concerns/questions are:
1) why do you need to redo the ceiling of the adjacent room?
2) i, too, considered air intake/outtake ducts. but i thought, "what if the intake cannot cool the room enough"? considering that 80% of my room's use will be casual, leisurely, non-tracking use, i thought it best to be able to cool the room. what would you do if your ducts cannot sufficiently cool the room?
if i were in your shoes, i'd probably buy a small window-type aircon, install it where you plan to have windows, then enclose the window/aircon in a small, shallow, sealable closet. so when the room is cooled, and it's time to track, i can turn-off the a/c, put a thick blanket over the a/c to effectively muffle noise coming from the a/c duct, then shut the closet tight. it's a little unorthodox, but that's what we budget-constrained DIYers do.
of course, it's just an idea. the masters get the last hack.
metal framing-wise, i am doing mine myself. bought a snipper (scissors) and a riveter. i bought the materials--studs, tracks, carrying channels, rivets, etc.--but will probably get someone else to do the ceiling. i could help you, but i am quite expensive, especially for someone without experience!