Is there a filter there that can be replace. read somewhere that there was a screen or something. so do i just clean the screen or is it just safe to drain the pan and add new fluid, without taking the pan off.

What I do every 30K is:

1. Drive X to warm tranny fluid.
2. Drain fluid from drain plug in tranny pan.
3. Refill with approx. 3 3/4 quarts fluid.
4. Drive X around to mix fluid.
5. Repeat drain and fill, replacing washer on drain plug with an engine oil pan drain plug washer.
6. Drive X around to warm fluid.
7. Check and adjust fluid level.

Some people spend about $100 for a professional flush, but IMOA it's a waste of money.

Try the Backyard Mechanic section.
The change gets closer to 5 of 9 quarts if you jack the right front corner up a bit.