Live in then rent questions

[Steven L.]

 We somewhat have a plan and have a couple questions.... our plan is to do a live in then rent a few times until we have 5 to 10 paid for properties.

We have been living in our current residence for about 5 years and we are interested in renting it out and purchasing a different primary residence. If we discover that landlording is not for us and decide to sell the first house in a year or so, would we have to pay capital gains taxes on it? 

question 2, should we start an LLC before buying house number 2 and putting that house under the LLC? and should we have an LLC setup on house number 1 before we start renting it?