One tenant claims people are breaking into the house and hitting her at night.

Given the details here I'd say no, you should take any development thoughts off the table because to do that is not something one simply learns over night, there is a lot to it. $209k is very cheap for 40 acres, so that offer could be a person interested for hunting land and nothing I'd get excited over, and I wouldn't assume it means anything other than you could sell it for $209k. 

A lot of little items, a big one being plumbing but I got someone to check the lines and all was good.

I say booking income because one property I was running reports on yesterday had 3 times the number of bookings from Airbnb but my direct booking income was 9% higher than Airbnb.

One is about a 11K and the other is about 70K.

Yes you can buy 2 properties as long as the combined price is the same as the net sale price of the one sold @Dave Foster is the expert and I use him for all my 1031 transaction.

Welcome to one of the great Community of people who helps each other. 

I am just one person with one experience but I will tell you in my experience the property managers I've dealt with have been the biggest thieves of all.

My cleaner sends me invoices once a month, and I pay by Zelle in one payment. 

One of the PMs I use, does some investing on the side and has access to his own set of contractors/vendors.