I am editing in these first two sentences after posting the rest of it. Wait for a professional because I may have omitted some important information or even made one or two mistakes.
jestem, jesteś, jest, są...
pod, nad (under, over - not so common when talking about persons)
z (with - quite a common one this, I reckon)
Often used with negation, but also with some verbs where one might expect accusitive.
Nie ma... (This isn't...)
Szukać... (to look for...)
I don't know. Fall back on this one if the thing or person is the subject of the sentence.