We file jointly, but I want the investing to be my business in my name.

It's increasingly hard to find genuine note offerings. 

Joint Ventured with a few partners to get this done.

Main thing for you is: - Have both you and your buddy talk to the same lender and get pre-approved to understand down payment options and what your combined budget would be- Decide how you want title held (joint tenancy or tenants in common) - do a google search on this to see which option is best for you guys- START SHOPPING!

Some investors I talked to are doing MTRs and STRs (this seems challenging with competing with all the other AirBnbs in CA), some are trying to do a Joint Venture and buy multi-family. 

I din't have enough capital to start on my own, so I partnered up and did a few joint ventures, sprinkled in some seller financing, and then syndicated a couple of deals, only to return to joint ventures.Pick a strategy, then a market, then start to network with all the brokers in the market. $400k is plenty to get started.Gino

You do not need a  mentor program, see if you can attend a  few meetups and then do a Joint Venture or equity deal with one of the investors there  and start from there.

Yes, you can file jointly if you or your spouse qualify as a Real Estate Professional (RE Pro) and share the benefits.To qualify as an RE Pro you must:1.

While not in TN specifically, I have assisted clients do as you have described: live in a property as a principal residence for 2 years, rent it out for 3 years, then sell.Based on the situation described, you would appear to be eligible for the MFJ joint exclusion on principle residence on your 90% share.However, in order to retain that ability, the house will very likely need to be sold (ie, sale closed, not just under contract) by the end of this month. 

If everyone is truly active, it is now a joint venture and you can have a local real estate attorney form an LLC for you (which is much less expensive).