When you purchase it, have it transferred into a Land Trust with the LLC named as the beneficiary as to avoid your name on the paper trail.

I think the structure would be better if you have the LLC be the beneficiary of a Trust that owns the property, this protects identities and at the same time asset protection.

If the IRA is borrowing money, the IRA beneficiary cannot sign a personal guarantee.

They are 50/50 beneficiaries of the Trust that the home transferred to upon their mother's passing. 

Although I think irrevocable trusts are probably the strongest.. you remain trustee your family is beneficiary I mean we all do this for our families right.although the single person with no real heirs I guess they have other challenges..  

When the property is transferred correctly, the property will be owned by the Land Trust, which in turn flows to the individual child Series, as Beneficiary of the Land Trust, and then finally flows to the parent Series LLC, as Member of the individual child Series.The Series LLC has benefits in lawsuit prevention, separation of assets, cost savings, and tax benefits.

The strategy I see many investors use is to purchase the property with favorable financing in personal names, transfer to a Land Trust and finally assign the LLC as the beneficiary to the trust.

Assuming you hold your rental property in your own name (not as a limited partner or as the beneficiary of a trust), AND, you actively participate in the rental activity, then you are allowed to offset your other ordinary income by up to $25K in net passive losses from your residential rental activity.  

Can the retirement account be a self-directed IRA that is a SEP IRA, Roth IRA, or Traditional IRA, or Beneficiary (inherited) IRA, or can it only be one of these?  

This may include ownership claims by owner(s) or record, their heirs, beneficiaries, successors and assigns as well as encumbrancers who are secured creditors and the assignees and successors.