you shouldnt listen to anyone telling you to play persona games in order, they have very little to no information connecting each other and both 3 and 4 are very similar when it comes to gameplay. FES is (factually, fight me) the definitive way of playing Persona 3, thanks to the additional content and much more fleshed out design when compared to portable, which instead doesn't have the additional after-ending content, becomes a visual novel basically, (aside from the dungeons) and has an optional female route. I personally played both, I 100%ed FES and ran through portable's female protagonist route. So, in my opinion, if you're enjoying the series so far and feel like you ended up enjoying FES and want more, you should play portable for the female route.

no, I highly doubt a steam release for the next few years or so. They don't seem to care much for 3 when compared to 4 and 5, they also seem to be pushing out more SMT content in favor of whatever 3 might have going for it anyways. stick to emulation for now