No need to test for fungus or insects, because you have them....you will have them, and they will come back. No seed for St Augustine is available, so dont look for it. If you cannot spend 500 to 1000.00 for a newly sodded yard, your options are limited. If you have a truck I have an idea....if you know someone who works at a golf course that is better. What you should do is find a local course (with nice turf) and see what you can do to get a few truck loads of plugs after aerification of tees or greens or whatever. Work out a trade if you need to. Get the "fresh" like as fresh as possible...plugs back home and rake out even. Water in good for days. Next thing ya know, nice lawn. If you can pay, my remark about empire zoysia stays.