I currently have 5 OM1's, 3 OM10's and an OM4T. They are all great but I have never had an OM2. I use the OM1 most of all and since I got the OM4 I rarely use an OM10.
I would say find a nice clean OM2 for your first OM and start collecting lenses. An OM1 will find you soon enough.
It's worth spending for a CLA on your OM1 and converting it for 1.5v Silver Oxide batteries. Once you use an OM1 you will forget about the others.
My advice for lenses is:
1) get a 50mm - the 1.8 are practically free and will likely come with your camera
2) get a 28mm or 35mm - 28 is more useful
3) get a 135/3.5 or the 75-150/4.0 - These are low cost and the 75-150 is way better than people think.
4) Stick with Zuiko. Very few 3rd party lenses were close to Zuiko quality and will leave you disappointed.