1) When I urinate drops of urine/water which I use to wash urine are scattered and some drops may touch my body, whenever I notice it I try to wash it but there may be cases where I can't feel the drops coming. Will they still make me impure? If yes then how can I avoid it?

2) When I wash my private parts after urinating splashes of water comes back to me(water when hits the toilet seat bounces back to me). Since the "Splashback" touches my upper parts of legs it is not possible for me to see whether the urine is there or not. I know that the toilet seat is najis but is the water bouncing back is najis too? How can I avoid it?

3) My question is that I do istibra but sometimes even after doing that drops come out does that make me impure or ruin my Wudu?

1) If you don’t see the urine or najasah and you don’t know it’s there then there is nothing to worry about. It’s best to check every time just in case

2) Yes if the water for sure is splashing from a najis area, you must wash wherever the water splashes

Avoid the water splash, or clean the toilet seat

3) If you see urine clean it. It doesn’t not affect your wudhu provided area being washed or wiped in wudhu is Tahir