1. You can start with either, at 4 years you have the option to do both
2. I recommend you keep work exprience to 3 or 4 bullets max per work ex. You do not need one buller per promotion ,you can talk about all 3 in the last bullet where you talk about your accomplishment! (good job by the way thats impressive)
3. Keep it standard - I would have one bullet per achievement type (e.g., Deans lists and other merit lists can be separate by semi colons in one sentence) BUT any major ones get their own bullet (e.g., class valedictorian)
5. Yes of course! All employment should be part of your resume!
6. Aim for 12
Feel free to DM me for a free resume template you can use.
All the best,