Im wondering how much to invest in my Roth IRA and SIMPLE, HSA, vanguard index funds, and how much to leave in cash and set aside for buying a rental property.

No simple answer to that. 

Was thinking about setting up a simple WordPress booking site, and I’ve downloaded a couple apps like Cozi (literally just downloaded it) and was thinking about setting up individual properties as “family members” etc but... love to hear what’s proven as easy and simple.

Keep it simple and renovate them just how you would any other rental unit (paint, appliances, hard wood floors) basic things that you can get from Home Depot. 

Once you have that, it will be easier to pick markets and property types. 

Unfortunately I didn't get to the formal disclosures because when they called to get my SSN to run my credit before disclosing it, I accidentally picked up the phone and said "Bay Equity Home Loans, this is Chris," was asked to repeat what I said... then the processor cursed and hung up on me.

So to use a very simple math example: if a full year's depreciation (house value, closing cost, less land, etc. / 27.5) is $365 then 4 days of ownership would allow me $4 of depreciation or do i use the full $365?

Not too hard but you’ll probably have to pick up the phone.

I just picked up a property for 100K and wanted to rent in Hemet but HOA put a stop to that real quick and we just flipped it for 170K.

Partnership taxation can be very simple but can also get very complicated very fast, especially when you get into substantial economic effect issues.