If there is .00 on box 7 and other boxes, what is the correct way to enter that on turbotax? 0.0 or 0.00, also box 18-20 has information, is box 15 associated state?

You should leave any amounts that are "0's" on your forms as blanks in TurboTax program (unless the screen specifically tells you to enter a zero).  Occasionally, there are some sections, where entering a "0" can trick the program into thinking there should be a number value associated with the box and you may get an error.  Now, if the number just ends in zero like 500.00 - you can just enter 500.00 or 500 instead.

And, yes, your box 15 state would be the associated state for the local box 18-20 information.