Would it be a good idea to transfer these rentals to an LLC in order to qualify?

@Jeremi Ramos do an addendum to your PMA that has all the Portfolios and Buildings on it.Be sure to include language though, that allows you to auto-transfer funds between the Portfolios/LLCs to cover your management expenses.Otherwise an owner could screw you on fees by letting portfolios go negative on their balances.

Your agent should be able to assist with this, but typically you need estoppel agreements to transfer the lease from the existing owner to yourself. 

Most attorneys in California advise against them as they cost about $800/year, and you also have to transfer a property into your personal name before a sale, so they do not help with anonymity. 

Same reason you have someone handle the mortgage, title transfer, inspection, etc.

Is this as simple as going to to county recorder and transferring it into my name?

Even though the property is under your Nevada LLC and you're the managing member, the lender will still need to be involved to ensure everything is cleared.Make sure the title transfer was properly recorded after your ex-spouse's passing, and work with your escrow officer to handle the mortgage at closing.

How difficult is it to transfer properties under my name to an LLC at a future date?

Deed is transferred to the buyer's name. 

I need to transfer a property from my sister to my LLC.