In theory they spread out costs instead of having big ones possibly hit you at once.Other risks are burnout, running out of money (usually because of outside issues, personal issues, etc).For me, I've been thinking/evaluating a lot lately the 'opportunity cost' risk of stepping away from engineering and business career to do the real estate stuff. 

Would there be an issue if she sub contracts some of the work to our father?

I've dealt with the same kind of issues.  

My family was very attached with the one we moved from, reason being the first home and the time and emotional attachement with the house we spend that we ended up renting and it’s still being rented after 8 years with good tenant and in great neighborhood.

First, our winters here in Boston can be rough - and tenants can be very sensitive to issues due to lack of insulation (cold spots and drafts) Second - big picture you may not have this property forever and will need to insulate before selling because that will impact how a potential buyer will value the home.

These are moderately complex - rewire, replumb, water intrusion, rotten kitchen and bath floors, reconfigure for master ensuite, and open kitchen/den.West End is very hard -- 100 year old homes, so lots of complex framing issues, super competitive, and require full gut rehabs or pop the top.  

I ended up deciding on a home equity loan instead of a help due to credit issues.

If this is interest accrued IE no payments .. then when is the balloon payment.. and what are you options if the home has not sold by the time the due date arises. also one lady in Atlanta who had well publicized issue with this company.. said that she had to front the rehab costs and then wait for reimbursement.. and that became a challenge since rehab contractors usually need money up front.. and wont wait for the draws.. 

However, the house I bought had several issues that a conventional lender didn’t want to deal with.  

I am only looking for houses newer than 1980 to avoid any lead paint issues.