Non-compete is far and away #1.
It's not so much that you negotiate it, but you have to know if it's enforced in the state/area (for physicians). An employer could put 20 or 50 or 100 miles in the contract, and many try, in a place that non-compete clauses never hold up at all (but you need to know this). Often, they will hold up for a reasonable radius, but they could put a larger one in your contract than the area typically allows (which might hold up to lesser area-standard radius, might hold up in excess, or could get tossed totally for being excessive... depends on locality!). It is seldom good to question or negotiate non-compete (raises alarm bells that you might become local competition), but you need to be crystal clear via attorney on how enforced or not allowed the non-competes are in the area you are potentially going to.
The situation you want to avoid when employed (PP pod... also MSG or ortho or large group ... but also even hospital employ) is having to move and/or find a new job under duress if terminated or not renewed. This is where having knowledge of the area non-compete laws (and an emergency fund) comes in. You'd
much rather have the option to take your time with the job search and move... or just work nearby or start up nearby. If you have to move, that often means break a lease, sell a house, yank kids outta school, partner job change, change all kinds of addresses, etc. Those things cost much more - both money and stress - than some piddly increase in CME allow or an extra day off or a small sign bonus that you may have negotiated. Even worse, non-compete (especially one which is NOT valid yet you think it is since it's in the contract), might make you feel stuck at a dead end job just to avoid moving.
Attorney, as mentioned... employment or medical focus office.
As far as the office, you have to look at the things that are not in the black and white: how happy are docs working there (or worked for the group in the past... TALK TO THEM, as many as possible), how is staffing, how is refer supply and marketing, how are area payers, do you like the office supplies and location and appearance, do the hiring and managing docs/owners seem legit. Hint: just because they appear to have money does NOT mean they're in a hurry to share it with you.