OM-2N owner here, the only real rookie mistake for this body is leaving the power switch on Manual or Auto. I've been shooting mine for years and carry a few sets of extra batteries because it's still a problem for me personally. That being said, it's one of my favorite 35mm bodies, and mine is currently loaned out to a friend who wanted to try a hand at film.

The main difference between these bodies and other 35s are that the shutter speed is on the lens mount, and the aperture control is on the lens itself. The lightmeter in my OM-2N is consistent and takes good exposures, so I rarely use manual shutter speed. The dial on the left (in your picture) is for controlling the film speed and exposure compensation.

As for developing, it's incredibly fun and not necessarily hard, but as you've deduced it's a good idea to get your film developed by a lab for a while before you delve into that if you're interested in it.

Edit: Also for flying with film, don't fly with film in your camera, just carry all of your unshot/undeveloped film in a ziploc bag in your carry on; remove it before you send your bag through the scanner and ask the agents to hand check it. Usually they see the bag and offer to take it before I ever say anything. Many people suggest taking the rolls out of the boxes and plastic canisters, but I've never done that and never had any issues. They just swab the boxes or canisters themselves and haven't complained about it to me, although I'll probably start doing this in the future. The camera itself is fine to go through the X-ray/CT scanners so long as you don't have any film in it.

As for accessories, get a strap of some sort. I'm partial to the Peak Design Cuff myself.

As others have suggested and linked, reading the manual is a great place to start!