Hey Jayb! It is great to see you thinking "outside the box" to try and generate a cash flow for your future endeavors.
1.) This generally depends on the success and seriousness of the business. If you are, for example, heading up a small community for a specific topic with options for premium accounts that you will make money from, this could be ideally balanced with the workload you would receive from school. If your business is something on a bigger scale and potentially needs investors for financial backing, this is a very hard task to accomplish while balancing school. If this is the case, I would not put "all your eggs in one basket", meaning don't drop out of school to pursue your business but rather find alternate solutions such as online courses, lengthening the time of your education (i.e., Take 5 years for a 4 year degree), or any other situations that could potentially decrease the workload on you.
2.) By the sounds of what you are explaining, it seems that you are trying to become an independent trainer? If that is the case, I would advise you (as with any business) to first register your business which you can do through a few different resources (cost you about $150-$180). After this I would get insurance for what you will be doing; you will need this just incase one of your clients is injured while you are training them to cover yourself.
3.) Be sure to get insurance that will cover what you will be doing. In your field, your client could potentially have a few things happen (pulled muscle, broken bone, etc.) while you are training them so it is very important to have proper insurance to cover you against these types of cases. Also be sure that when you have your clients sign contracts, you also have the proper documentation needed when personal training someone (PARQ, Informed Consent, Health Questionarre, etc.).
4.) These costs vary depending on the amount of content covered, the lawyer you visit, what services you need from them. As Southern said, be sure to research and do as much homework as you can before you seek out a lawyer.
Good Luck!
Kristian Bouw
CEO & Founder
Evitca: Fitness, Simplified.