2002 Acura TL P0740, P0730 Please Help

I just bought an 02 Acura 3.2TL V6 Automatic from a private owner. The guy who sold me did not let me know that there was a problem with the transmission. At the time I bought the car, the Check Engine was on already. The owner of the car at that time told me that he just replaced the front tires and the Check Engine light came on after that. I was concerned that there is a problem with the transmission and repeated ask that owner several times that he really sure there is no problem with the transmission and he said there is no problem at all (is he lied to me?). So bought the car and very proud to have it.

I drove home and put on about 50 miles in three days and notice there is a problem with transmission (Excessively burned fuel-about 1/8 of a tank in 20 miles- the faster the speed the more fuel burned, then came to problem with gear shifting, and then the TCS light came on). I then check the oil level, transmission oil show in the upper mark, engine oil was Completely Dried-will this damaged something? So I added the engine oil.

Next day on startup gear shift ok and drive normal, after driven for a bit then it won't shift and the TCS light came up. I turned off the engine then started it again, TCS light went away, Check Engine remain on as it was, and the car driven again but tend to have problem again after an amount of time driven.

I brought to a tech for diagnostic they told me that there were problems with Torche Converter Clutch Solenoid Circuit/Open-code P0740, and Drive Gear Ratio Incorrect-code P0730, and they also told me something with the Transmission Oil was burned. They told me it very costly to replace the transmission.

So what is the most economic way to fix this problems. Should I have the Transmission and Engine Oil Flush, Replace the Solenoid, or put on New Trans.
and how to make the gear ratio correct?
What is the solution and cost to get these things done to bring the car back to normal? Please help. Thanks in advance.