Find out about taxes on the property are they under a special tax cut? 

Tool wise all you need is a angel grinder with a masonry blade to cut and shape regular blocks for the back post.You could also easily replavce all posts yourself with 6 X 6 PT.

He told me that if i want my 7% return, i can simply rise the rent of the currently renter, that will remain with a 3 year contract in the property.

Razor cuts are really tough to get out and sometimes never come out. 

I had insurance policy that covered the loss of rent and the HOA cut us a check to renovate it ourselves.

YUP  exactly anyone who thinks low value  assets are passive simply does not know what they don't know or are in denial or will get an education real quick. 

However, I can make contributions via a back-door rollover simply by contributing to my pre-tax IRA account and partially rolling those funds into the 401(k) account. . 

Coinmac (or whatever they're called now -- google 'em) will put machines in there at no cost to you, service them, take the cash out, etc and mail you a check for your cut (they have different profit splits you can negotiate) .If you just have a small building, it's not likey worth the cost of doing a 'smart washer' that can take payment via venmo/paypal/applepay but they do exist. 

The HOA had tried unsuccessfully to get insurance to pay for repairs, but insurance has denied the claim.So my question is whether or not this is something that should have been disclosed legally, or whether it is simply a case of "buyer beware" and now it's my problem to deal with $$$$$$$$$$.Anyone have insight? 

Then take a cut of the transaction fee.