Is a 50/50 split of all cash flow and appreciation appropriate? 

So your renovations will be from cash flow.  

This income  would likely be coming from a K-1 (form 1065), and flowing over to your Schedule E on your personal returns.

However, ensure that the transition to 6% interest after 2 years is manageable with your projected cash flow.

IO also is an option if concerned about monthly cash flow. 

Yes, you will pay for commissions (which are 100% negotiable)- I like the idea of approaching the agent for the new buy (if in the same area), who might give you a discount on the listing if you also buy from him or her.There are programs out there that help you BUY before selling, they will give you a 20% downpayment and money for repairs on your existing house- you'd have to use an Agent and them that is affiliated with them and they act as the straw man lender- check out Knock.com, Ribbon, Orchard, Homelight, etc- and there are others- I'm not sure which are available to you in California.In most states, homes are sold "As-IS" anyway), and all you have to do if you cannot make repairs is to properly DISCLOSE what you know isn't working, so that buyers can take that into consideration in ADVANCE of contract, in both their offer but also to save them surprises later on which could cause them to back out- if they know in advance and all is disclosed, there's less chance of that happening.

To combat this problem, a great management company who will have your back and navigate the ebb and flow of the ever changing climate of these rental sites is essential.

It cash flows but is very tight. 

Official paperwork should be prepared with a real estate lawyer, and financial examination should take into consideration interest revenue, tax consequences, and market circumstances.

It is a combination of a CRM, deal flow tool, and broker commission tracking.