sell the ones that give you the most trouble, and roll the money into the others.

I haven't run the numbers yet but will do so when tax time rolls around.

Don't sell at a loss, play catch up then go ahead and roll this into a better investment. 

Rolling over profits into a new property?

Get 3 estimates, some times they will only  replace to the point of proper old sewer line only that can save money  BIG time   .They will add a clean out  next to the house one out farther where they stopped the new sewer line  replacement .As far as suing  any one on such a manner need to figure out what the legal  cost are plus what  percent chance of success then decide  of you want to roll the dice  unfortunately this type of scam happens a lot now a days .

Lenders are gonna want to see profit and loss statements, rent rolls, property condition assessments, the whole nine yards.

One issue is the challenge of qualifying, as conventional loans will have DTI requirements, income requirements, loan size limits, and loan amount limits that investors looking to scale a portfolio run into as soon as the financial freedom snowball starts rolling.

Any general advice you can share on getting this ball rolling? 

Forcing solar and wind creates higher electricity costs and rolling blackouts.The vast majority of landlords are doing the right thing.

Just because we tell people how we do things does not mean we are rolling in cash.