A lease is a contract and the best, simplest and legal way is to wait until the contract expires and so a new one.

That would be the simplest way. 

You'll still need a strong understanding of building codes even for the simplest of projects, so keep that in mind.

This is the simplest method, but it also means your tenants are more likely to abuse the utilities by leaving windows open with the heat or A/C running, leaving lights on, ignoring the toilet that constantly flushes on its own, etc.3.

That's probably simplest,  if they just have a mortgage. 

You can just put 20% down if you want, that's the simplest way to do it, but value add and refi's will help you scale whether you pay cash or do a conventional loan with 20% down, I'd try to keep recycling those funds until you are 100% FIRE. 

Selling the property at full price to the LLC is the most likely and simplest option that we will probably take, just hate losing the low interest rate.

-HH is a relatively simple strategy (it's arguably THE simplest strategy), which makes it much easier to succeed.

This is the simplest method, but it also means your tenants are more likely to abuse the utilities by leaving windows open with the heat or A/C running, leaving lights on, ignoring the toilet that constantly flushes on its own, etc.3.

Problem is however, locally for me, the simplest houses (3/2) start well over $525,000 (excluding a minuscule percentage in the very very bad neighborhoods).