Purchase price: $59,000 Cash invested: $69,000 Sale price: $222,500 Beautifully renovated duplex in Historic Downtown Louisville.

Were any of the sentiments based on historical examples?

Historically that is almost free money. 1% or so in the rate should not kill a deal or you probably didn't have a deal in the first place. 

.- Historical financial information on the property, a T12, a YTD P&L and a rent-roll.- Any additional information you may have such as an OM or an old appraisal etc.- Leases (not necessarily needed at first, but we will need to review these).On the sponsorship side, we need to know -- Net worth and liquidity of each sponsor with a share of 20% or more

If in doubt on being able to pay the HELOC off soon, I would do a refinance using a 30 year fixed on the primary residence to pull money out and use that money.I am leery of variable rate loans when we are at such historically low interest levels.Good luck

When I go on the Los Angeles County Assessor's website, it seems I cannot access information regarding historical data of property tax/rate for a specified property.

I won't be investing in the riskiest/most supportable asset subclasses such as hotels, and tilt my portfolio the ones that have historically been more stable such as multifamily and single-family housing.

I haven't used them to do any transactions but they are highly knowledgable about the market and understand historical trends. 

I am aware that mutual funds can be good as well, but I do not feel comfortable putting money into the stock market. ( I know real estate markets can fluctuate but historically aside from the crash have been relatively stable and increasing at a consistent slow rate )2) I have two sisters but I will be the one to take care of my parents when it gets to that point in life and I want to be sure that money is not an issue when it comes to getting them top shelf care, if needed. 3) Real estate gives me motivation that is long term rather than a project at work that is not infinite.

Your cash flow would decrease (due to higher LTV) but the decrease would be less than the historical appreciation of the S&P 500 (or other such investment).When you wanted to access the money it would be available (because I had liquid as one of the qualifiers).BTW I looked into HELOC on investment RE a few years ago and agree that there were not a lot of places offering it.I suspect you have done more recent research than anyone else on this site.Good luck