Can someone provide me with some resources (i.e lawyers, title companies, etc) on how to do sub-to deals in Texas?  

I can't answer all your questions in depth - some are best suited for your accountant and lawyer- but I will say that there are a number of resources.

Hello,I hired a lawyer from Upwork.com who has received many 5-star reviews.I asked him to write a lease agreement.

Requirements for 7 are income under 80k for single. lawyer says should be fine, but you never know.

Is it worth getting a real estate lawyer, sending a demand letter, going to small claims court, suing, or doing anything like that?

But if you have to, consult a local lawyer and get the process started asap.Security?

You can have Home Owners and Flood Insurance and the Big Bad Wolf will blow your house down and then, you need to pay a lawyer to try to collect damages from Insurance who may never pay you. 

I would also discuss with your lawyer about providing a General Warranty deed.

If this is Hamilton Couty, there are three or four lawyers who have regular dockets in the Eviction room.

Highly recommend hiring a lawyer that knows CA landlord tenant laws inside and out in your specific area.