Some don't, some may charge you a fee or have restrictions on the type of tenant,  and some HOA might not be financially sound which will cause a problem for your mortgage lender. 

(there isn't any product being moved or sold so its a no pressure thing, just informative) I am curious to see if they talk about any upcoming restrictions that may pop up. 

@Gregory Emmer Thanks for the tipThe plan so far is to buy 4 at one time since that is the limit imposed by banks now days.

To answer your question quickly, no you will not be restricted to 50% LTV when refinancing the current debt as you transfer title from your LLC into your name because you own the LLC 100% (min 25% ownership is needed) so as long as your LLC has held consecutive ownership in this property for a min of 6 months prior to the disbursement of the new loan (AKA prior to funding).

Are there any restrictions from the US government or IRS or anything I have to be aware of? 

There are so many guidelines for so many programs that a lenders office can look like a law library if they chose to print and bind each program independently.The initial statement referencing the loan amount being restriction to not exceed the initial purchase price is as indicated above based on the "Delayed Financing" program.

Check for restrictions in the chain of title. 

If selling a house, are there restrictions against advising the buyer of certain lenders to use?

How did you impose your rules or philosophies with the tenants? 

Some impose deed restrictions.