I keep the houses we live in and use separate from those we rent. 

After you can push them all you can cut expenses (Separate utility lines and charge to the tenant?)

I'm just curious how some of you experienced property owners determine how much liquid money to keep on hand for a given property, if there are important reasons to keep that money in a separate or LLC bank account, etc.

If so, the hit up every single local bank because they will be happy to help (as long as you have good credit history and if you are just starting out then they are stoked to see a separate steady source of income and not all reliant on the new investments).

Other than 1) Actually firing the PM, 2) Having a separate bank account to hold the tenant's deposit, 3) Having the old lease end and new lease start the next day...Are there any other considerations I need to take into account?

When convert to a single family home can we still keep the separate electrical and gas line?

Separately there are closing fees that may differ from market to market and are covered and documented in a meeting prior to allowing any access to inventory. 

Some have been on the market for 2 weeks-4 weeks, but they aren't priced right in my opinion, just slightly too high.On a separate note, I had a lady reach out to me that hadn't toured my house yet.

Should I combine it with the other four and have one mortgage or should i keep them separate?

Seeing as how you can rent out your personal home, or ANY home you own for up to 2 weeks and not have to pay any taxes on that rental income, I see no reason why you would be forced into a separate loan product with inferior terms.