As far as installing them that is up to you and your personal preference of whether or not you want them.

Preferably ones that don't require a lot of time to get started with.

Hopefully you hold title in a tightly maintained LLC, that's preferably NOT a 'sole member' LLC.However, it does need to be addressed immediately, a local investor friend of mine just got nailed $2000 for failure to clean it up on time & his units are empty, & he can't rent the units or sell them until its done.It appears that his local Bldg Inspector was roaming the 'hood for violations & had several local landlords in housing court.Lead Paint ramifications are a serious issue that is haunting our local landlords, esp the uninformed.good luck & keep us updated...

I formed a single member LLC and would prefer to transfer ownership of the condo to the LLC.

Would you prefer a duplex, tri- plex, quad or a larger apartment building or commercial??

We currently have about $30k (which does not include our 6-months emergency fund) that we are willing to use to invest and I would prefer a multi-unit but am willing to purchase a SFH as well.

If it was a family with young children, they preferred the yard.

I don't play in the appreciation market personally I prefer cash flow, and the 50% rule doesn't get you to a specific yield either it just says what your expenses will likely be.

Do you all prefer rentals with or without basements?

The seller's putting you in the position where you have no other choice.