Can i rent a car at the airport with out a plane ticket?

Yes, but keep in mind that it's sometimes more expensive to rent from the airport than other locations due to airport taxes and fees.

I use Hotwire and always pick up from DFW .. More choices..

Yes

Yes you can. Would look at other locations since there is a premium for renting at the airport at certain places.

Of course

Yeah I do it all the time

Yes you can.