And can hacked HA legends be poke transported?
Nope it was only obtainable by hacking. To answer you second question I must say it depends. If you make it like 252EVs in each stats then no but if you make it legit yes. I actually got a Volt Absorb Raikou (with pokerus) that passed trough pokebank. But I traded it for a shiny but yes.
Not yet, I believe. There might be an HA tornadus, thundurus, and landorus event in the future, sorry. And no, hacked legendaries(or any hacked Pokemon really) can be transferred through pokebank.