Contributions can be made as both employee and employer contributions (since you wear both hats):The employee contribution limit is 100% of your w-2 wages up to $19,000 (or an additional $6,000 if you are 50 or older) provided that you are not making employee contributions to another plan (e.g. if you have a day job with a 401k plan). 

As far as liability insurance is concerned, I would recommend the highest limits offered.

Also, everyone has their limitations.

You have lease but option to buy at a set price for a certain time limit into the future. 

Remember, if you are relying on your own cash or others cash, you are limited to that number. 

No limit on mortgages. 

Our credit scores are a little low for traditional or even fha financing...plus the financed amount would exceed fha limits anyway.I can get a hard money loan, repair credit while we fix up the house then refinance in a few months.

@Michael NotoAs mentioned, the real thing you want is for them to have liability insurance, not only to limit your liability exposure for injuries on the property, but, more importantly, to cover your property if they cause damage by starting a fire. 

@Brandon EllisThere are major limitations in coverage under the Federal Flood Insurance program that may affect your decision. 

Appreciation is limited as it is imploding demographically.Countries like Canada, Australia, NZ are well positioned for long term demographic and economic growth, but they are not as affordable as growing US cities like Charlotte, Atlanta, and Indianapolis at the moment.