They may require other things like a closet and air intake/exhaust vents.

For example:General-Filters (furnace, air conditioning, oven exhaust, refrigerator, and water)-Stove burner when the “eye” needs simple replacement-Batteries and remotes that service the premises-Fan and light pull strings-Smoke and carbon alarms testing and batteries-Ensuring appliances are properly plugged in, hooked up, and used-Removing dirt, debris, and lint in and from connection pipes (e.g. clothes dryer)-Tighten loose screws on all home functions (e.g. doors, hinges, handles, socket -Balancing off-balance appliances-Cable, internet, and phone jacks-Fire extinguishers-Systems operation (e.g. security, irrigation, HVAC)HVAC-Monthly A/C filter and drain line maintenance Electrical-Reset “tripped” GFI breakers-Light bulbs (throughout and at the end of the tenancy)-Blown fuses-Reset breakers in the outside and inside breaker boxes-Socket and plug outlet coversPlumbing-Unclog drains or toilets-Caulking around tubs and showers as needed-Gas pilot lighting-Leaky faucets and shower heads-Toilet flappers, handles, seats and seat lids, tank lid, and flush kit-Sink and tub stoppers-If septic tank present, use RID-X as directed on consumer box-Proper cleaning of garbage disposal-Loose faucets and sprayer heads and hoses-Faucet filters (i.e. aerator)-Open exterior plumbing clean out when necessary (e.g. sewage backup)Exterior-Routine lawn (and pool) maintenance-Adjusting sprinkler heads as necessary-On the last month of tenancy, tenant must perform required lawn maintenance no sooner than 2 days prior to vacate dateThere’s a lot to consider as a landlord.

[List not exhaustive]. 

For me when it came to hiring an attorney it was because I had exhausted all hope of our JV actually producing anything.  

, roofer to see if they are getting into the exhaust vent on the roof?

There are a ton of strategies but you being in Southern California, I'd recommend you exhaust every effort of trying to get started with a house hack here than going out of state. 

I understand BiggerPockets has calculators, an exhaustive list at that.

An Umbrella policy provides additional coverage if the limit on your Homeowners or Auto policy is exhausted due to a covered claim. 

I would, personally, let him exhaust all his funds on the purchase and then you come up with a loan that finishes off the acquisition financing and then holds the rehab funds in escrow in an account you and your brother sign off on for withdraws.I do not think I'd put a lean on the property. 

Prolonged enthusiasm can be exhausting (failed offers, tours, travel) one way to remain engaged is to stay connected and in constant communication.