@amp107
Let me try to answer your questions but first I really like your idea of sending your founder to University.
I have sent my Sims (personal preference) to university from home. Moving to campus is something I have not tried yet.
I found some information on the challenge website that hopefully will help you decide how to proceed.
Your scenario is unique to anything mentioned in the rules.
My thought would be to go with your original plan and adapt as needed.
(Also my personal preference is to turn off aging while at university.)
Discover University Updates
*You may send your Sims to college or do college from home. HOWEVER if you send your Sims to college one of the Sims sent MUST be the heir as time will continue to progress for the rest of the family.
*Once you move your Sims into college you cannot move in other roommates. Only the ones you sent (it can be more than one).
*Your Sim may enroll in any university.
*The Legacy Legacy Handicap added to points. Want your Legacy family to have its own Legacy college? Choose either Britechester or Foxbury as your family’s Legacy college when you make your founder. This can be the only college that your Sims can attend throughout the challenge. So plan majors accordingly! Also make sure to donate money to the college that you choose.
Reference: https://simslegacychallenge.com/sims-4-legacy-challenge-gameplay-rules/
Last Updated on May 13, 2020
As for the gameplay rule updates, the biggest changes here are that you will no longer be required to buy objects (Knight of the Octagon Table, etc) to get your Sim’s money down. You can just use the money cheat to change it to either §1800 for a regular start or §0 for an extreme start. You can also start on any 50 x 50 or 64 x 64 lot that you wish.
Reference: https://simslegacychallenge.com/legacy-challenge-rules-scoring-overhaul/