I've been out of college for three years now and my two cents on the matter are:
-having a college degree is a basic qualification for a lot of jobs. my wife doesn't have a degree and has found it very difficult to get started into a good job because even the most basic of jobs want people to have a bachelors degree. if you have the money to go, it can open a lot of doors. you may appreciate this more further down the line. for a long time i debated college, but ended up going. I spent two years in CC and transferred to a 4 year to save money. at this point I am happy I went because I have more opportunities and choices now.
-while you're in college you need to network, network, network and with the right people. if you want to have success in life then you need to surround yourself with likeminded people. network with people who want to achieve something in their lives, collaborate on projects with people. going out and binge drinking with the losers isn't networking. i have people i know that think they are networking by going out to the club every weekend, except all the people they meet are losers who aren't going anywhere. I worked my way through college and graduated debt free and with money in savings, however looking back I realize that I missed out on a lot by keeping myself too busy and too isolated. as a result i don't have any close friends from college. the result of this for me has been that i have seen friends who did network in college who used those connections to land good jobs after college.
-college degrees are a dime a dozen these days and will not save you. when my parents and aunts and uncles graduated school in the 70's, a college degree in anything pretty much guaranteed them a good job. for our generation thats not the case.
-student loans are a racket. if you can afford to go with minimal debt then it may be a good investment for you. if you have to take out a lot of loans i would suggest get a degree in something that translates into a good job, something like accounting, hard sciences, that way you will have a good shot of being able to pay off said loans soon after graduation
Considering your position with your mentor. I might suggest spending 2-3 years working with that person and seeing how it goes. You can always go to college a few years down the road if the REI thing doesn't pan out like you think. If you are 19 now, work REI for 3 years and you'll be 22, finish your last three years and you'll be 25, not too bad. I took a gap year to work and save after high school, spent 3 years in CC and two years at university and graduated at 24, two years behind my HS class that went straight through