These parks will have specific rules on what you can do and what they want you to do. 3.

This is common, there are usually some justified reasons to get tenants out such as a major remodel or if you plan to live in the unit yourself, however you should have read the rent control rules and had a plan in place before purchasing the property. 

What are your percentage rules of thumb for 1) New house/unit, 2) 10- to 15- year-old house/unit, and 3) older house/unit? 

At the meetup there was a speaker who was talking about his success to financial independent and when he went through his list of rentals he bought over the years it left me with a lot of questions. 1: Most of his rentals he bought in B+ to A area's in the 300-450k range in Florida.2: His numbers just didnt make sense, one deal he posted it showed literally like a +$5/month cashflow only....So afterwards i started to talk to him more and he mentioned that he is not the type that invest in cashflow, he is a equity investor... intrigued me so i asked more questions and basically he went on to explain to me that he buys properties that need a little bit of work, but have built in equity in the deal, but he has 4 main rules he goes by... 1: If the Roof is greater than 10 years, he always puts a reduction in his offer for a replacement roof.2: If the A/C is older than 5 years, he always puts a reduction in his offer for a replacement a/c.3: If the house is older than 30yrs old, he always puts 10-15k reduction in his offer for a water line replacement.4: He refuses to buy houses with pools....Anyways after a bit of talking he explained to me that he buys larger 300-450k houses, because most investors are educated to not buy them, so there is a lot of room to wiggle on the deals due to lack of competition on offers and most people in that price range are easily able to be purchased with a few % out of the deal to skip agent commisions..Example he gave me, he recently bought a 455k deal for 405k, but the ARV 535k, because he talked them down in needing a new roof, and a/c and offered to pay cash instead of going through an agent if he would drop 4% off the price for that... 

Some have hefty pre-payment penalties and other rules.  

The Operating Agreement must contain language sufficient to address IRA-related issues concerning Prohibited Transactions (26 USC 4975), The Plan Asset Rules, the allowance of subsequent or additional Capital Contributions and Unrelated Business Income Tax (including language that ensures that the Manager of the LLC will prepare and file all necessary tax forms with the appropriate taxing authorities, Federal, State and local).

The total of his small deposits with their rental at the customary rate of one fourth their due for each four years, had now become a thousand and forty pieces of silver."

Just wondering what’s a good rule when it comes to having reserves.

But doesnt being in an LLC that you have less than 50% investment in get around that rule?

It would be well advised to talk to someone and learn Exactly what the rules are, even if you need to pay a local attorney for an hour or so of time.