The Beseler 23C can do medium format as well as 35mm and is a great enlarger, imo. If there happens to be a Beseler 45MX or such available, it might be better to get it because using MF and hanging out on APUG will eventually lead to large format in many cases. I have two enlargers now because of this.
I use Schneider Componon-S lenses for 35mm and 120.
Once you start using it, you'll have a better idea of some of the little things you'll need, but I swear some things breed if you leave them in the dark long enough. Somehow, I started with two enlarging lenses and have at least 7 now. I have no idea how many trays are down there (I think I only bought 7) See what you can get with an enlarger and then trade that for something else later. In your early attempts, it won't likely be the lens that causes issues. Once you get the issues worked out, you can move up if you need to.