(Budget, Resources, Abilities & Time)Prior to beginning your search for an investment property, you must decide how much of each of these you have, and what you are willing to provide towards this new investment endeavor.Budget is obviously how much you can or are willing to allocate towards a investment property. 

Have that person on the llc and have an arrangement of how the money would be allocated.

Is there a good percentage I should use to calculate these numbers (i.e. 10% of total rent should be allocated for repairs)?

If I turned down deals that would have profits of 400 per month per house with no money down (regardless if its seller financing or thru hard money buying), I would only have about 3 or 4 houses instead of 19.That is my exact target number for a good deal.And I typically have to finance the thing twice to do it (hard money and then the perm loan).The fact is if you're allocating more than 400 a month per house toward vacancies and repairs, then you're going to have a real tough time ever getting into investing in the real world.And the fact that he's picking up 3 in one fell swoop is even better.

Be sure to properly allocate your allowance. 

Your closing attorney or settlement company will handle the proper allocation of funds once they have a signed addendum on how buyer and seller have agreed to handle it.  

I think Allocated Utility Service would be my go to.

Any tax beast opposing your allocation will need to weigh the benefit of time and effort expensed in assessing the issue diferently, not worth the effort of any auditor I'd think, unless you had other issues in question.

How much time do you have to allocate to real estate investing??

You have one set of books, one tax return that flows through to members or as a corporation, one bank account for operations, no allocations of expenses to various LLCs, lower time required for maintaing the llc books, meetings I could go on and on....If any attorney suggests such a strategy, I'd say they are likely milking you into future leagal assistance, and an accountant for additional accounting time.