Ouch...Yes you can put tranny fluid down the dipstick tube to fill it. That's the only way to fill a 700r4. Not really sure what to tell you about if it's hurt or not. You should most definitely pull the pan and drain as much of the old fluid out as possible, especially if the fluid that is in there looks black or smells burnt. Put a new gasket and filter in and add new fluid. Other than that, I'd say pray for the best.
If the current fluid is black or smells burnt, I hope you know a good tranny man.
Advice for the future: Check all fluids before you depart on even an "around the block" trip. Even the brake fluid, if you can't stop you'll be in big trouble.