would it be possible to swap a mazda 3 engine in my 95 sentra
and could i get the automatic\manual transmission

I guess anything is possible with enough money, but the real quesion is why? It doesn't make good power, it would cost a shitload to swap, and it's HIGHLY unlikely that it will be as upgradable, strong or as powerful as the other swap options you have *cough* sr20det *cough*.

get a GTiR SR20DET and a mazda 3 will bow at you!

Seriously, the sky's the limit; you could put a fucking submarine reactor on it if you had the dough. Honestly, going to all the work of swapping in a Mazda3 engine in wouldn't be worth the minimal power gain. You'd be better off spending the ~3k on a turbo kit or just getting an SR20DET.