I'm a bit displeased with the vita myself, unless you're planning to hack it. Games are expensive, no support for games you may already own that are released on the Vita (you need a 'vita' version) and the catalogue is awfully small.
This post is just... Wrong in multiple ways. Most games are < $20 unless they were just released. Sony offers a feature called cross-buy, which many developers (mostly indie) agree to, which allows you to digitally buy a game once and play it on multiple platforms. (PS3, PS4, PSV)... If I'm not mistaken, Sony is the only one out of the big three to offer such a feature! The catalog of games largely depends on your taste; if you're open to new things, enjoy JRPGs and indies, you will find a lot more on the Vita. The Vita is doing much better in Japan, and as a result a great deal of the games coming out are heavily Japanese. You should know the system's game library before you commit to it. It's perfectly fine to say "the games on the system don't interest me much", but the way you made those statements as if they're facts just feels a bit misleading to me...
Anyway, on to the actual questions!
Will a hacked vita work with remote play via Internet or WiFi, or Will i need to update to OFW? (remote play is biggest factor for getting one)
How is the PSP ISO compatibility for hacked VITA?
I have a hacked psp. Is it worth a hacked vita to emulate psp on it? What are the benefits compared to PSP ISO emulation? Vita piracy doesn't interest me actually
Are any of the exportable games still available? Knowing Sony, wouldn't they pull them and fix the exploit Ala Nintendo?
What's the best version to own?
1) There is no CFW for Vita at this time. To use remote play, you will need to comply with Sony's restrictions. I assume you need to be on the latest firmware, or at least you would need to if your PS4 is on the latest firmware.
2) Nearly 100%. I'm not aware of any exceptions, but I suppose there might be a few.
3) There aren't really any benefits that make it worth it, except that you can have your PSP games and/or emulators all on one device. That comes with the trade-off of filling up expensive Vita memory card space, though, so there probably isn't a compelling reason for you to hack your ePSP.
4) Firmwares 3.52 and below are vulnerable to an email exploit which allows installing homebrew using any 1 PSP game/demo. You have to be on the latest firmware to download from the store, though, so the only way to get said game onto the Vita is by transferring from a PS3. Firmware 3.55 (the latest firmware) has exactly 1 exploitable game, available in US and JP, and it is still available. It is called Mimana Iyar Chronicle and costs $10.
5) The original 1000 model has an OLED screen. The slim 2000 model is lighter, has an LED screen, and slightly better battery life. Some people say the screen makes a big difference (usually in favor of OLED), while others don't notice it at all. A few rare specimens say they even prefer the LED screen.
Given that you are uninterested in native Vita hacks and already have a hacked PSP, there isn't a good reason for you to stay below the current firmware. If you have a PS3 and the Vita you buy isn't already updated to the latest firmware, you might want to install ARK for free on the lower firmware in case you ever want it, then update. Just be aware that updating beyond 3.51 closes you off to the one native hack available, so you lose the benefit of future homebrew on the Vita that utilize more power than the PSP. (E.g. smoother-running hombrew games and emulators)