The limiting factor for our investment is the 6 months reserves required for our current mortgage and the mortgage of the investment property.The lender recommended opening a HELOC for the reserves.

If I don't own the house whether I used my money or someone else's money to buy the house, I am limited to buying it only to wholesale it.

Are there limits on the type or size of the business?

I spent a lot of frustrating nights, not using the right materials, measuring wrong.

My partner is funding most of the down payment and closing costs as a limited partner.

The limits are determined by state law.If an IRA owns an asset such as real property, a tenant sues, then they are suing the IRA. 

The loan limit was one of the reasons I was wondering if an LLC would be a better fit.

As used herein, "permanent improvements" shall include, but not be limited to, all repairs, improvements, and equipment attached to the property as fixtures.

Based on my limited experience, it looks like a good deal that I should go after.

I'm no expert on the matter but if you are limited on information on the property to access what kind of cash flow it can produce I would stay away.