Only before some letters.
It may sometimes sound like that especially in rapid and careless speech, but rather try sticking to what's actually written. Polish rather doesn't have sounds that are deliberately pronounced differently than what's written. Only sometimes it's 'too much' to pronounce the word very precisely, for example 50: pięćdziesiąt turns more into piełdziesiąt.
Well, it can mean 'to judge' literally - i.e. in the court. But not like 'we were sitting in the corner of the room, judging people quietly'. I think simple "oceniać" would be used then.
"Sądzić się" is to battle someone in the court.
P.S. "oznaczać", there's no such verb as "oznać" :)