Constructive kept me strung out for over a week, submitting doc and after doc after doc, only to tell me at the end, "Well, it doesn't look like you have enough liquidity."

I had to deal with a lot more issues than I've ever had in non-S8 rentals like extensive property damage and also bed bugs, roaches, drain lines completely clogged up by grease (I learned what sewer worms are, look it up), spray paint art on walls and food on ceilings, noise complaints, police at the property, removing dead bodies, etc.  4.

One being that I personally needed liquid resources(cash).  

So when considering your entire "capital stack" I think it is worth opening up a HELOC on your primary residence to make your equity more liquid, whether you end up doing another house hack or staying in your current home forever. 

B) The pros and cons of having two properties instead of one (especially in terms of liquidity).

When rates are high you can charge higher rates, offer short term loans (12 months) and have some liquidity and make a decent return

For your first deal I would reccomend having about 50% in cash or liquid assets. 

It's a great place to store your cash until you find the right opportunity that works for you plus all the other benefits it provides (not least of which is flexible terms and liquidity when you DO find somewhere to invest your money).

How easy is it to liquidate into cash to make acquisitions?

I know others who have also found using spray paint works to seal in stains.