and if so, what percentage could we claim as a loss? 

What percentage is reasonable to find the deal and walk him through the rehab and refi process?

You could even ask an experienced wholesaler to look it over.I agree, but I think a lower percentage than 5% would know what to do investing and remodeling.

Multi unit changed the math for me in some calculations.One exception to the rule above is syndicating with a PM who also is an LP and receives management fees as a percentage of profits (rather than typical PM fees).

What you do with your money is your business, except the IRS wants its percentage of the profit (well, less any other deductions that apply).Don't forget that investment properties have to take depreciation. 

Your husband should review the plan documents or contact the plan administrator to understand the specific rules that apply to his 401(k) plan.Loan Limits: 401(k) loans are usually subject to certain limits, such as a maximum loan amount based on a percentage of the account balance or a set dollar amount.

and what percentage of the units can be rented out? 

By putting down a small percentage of the property's value (e.g., 5%), you control 100% of the property and benefit from 100% of the appreciation, despite the bank financing the majority of the purchase.What do I mean by that?

What percentage of leverage do I have?

I have also gifted a percentage of the house to him each year, so that he now has a larger ownership %.