Like you, I was concerned about potentially triggering a due-on-sale clause with the lender.However, I spoke with my lender, and while he confirmed that technically this could trigger a due-on-sale clause, he also mentioned that in practice, it’s very rare.

A fixed-rate manager might let you retain control over the booking process while saving on commissions.If direct bookings are a primary goal, having someone motivated to push these (beyond the traditional channels) is crucial.

You can raise capital through family, it’s actually a very common practice.

But it’s most important to have the practicality and shrewdness to see and take advantage of it. 

It might be work just looking for deal analysis practice to see if you get closer to a number that works.

To start, research local markets, and understand property taxes, rent control, and cash flow.

I'm a college student, and I plan to start investing in multifamily homes once I graduate, and I recently started looking at deals on Zillow just so i can practice underwriting.

To answer your question, the advantage the GP has is control, and the ability to gain wealth from their equity position (hopefully not so much for asset management fees) by selling at a big gain.  

If you really don't value your agent's ability and think you can do it better, it's likely best that you 1) interview more to find one that you do trust, 2) go through the listing agent, directly, if you're that comfortable with handling your side on your own, or 3) maybe get your license so you can control your side of negotiations with the proper tools needed (MLS access with agent info, showings, contracts, tax records, uploaded listing docs like surveys, disclosures, broker assistance for questions, etc.).

As far as the practicality, you want to look for homes with somewhat separate spaces, and theres an app now called padsplit that I've not used but have heard good things about to help with the management nuance of it.