samurai's are any good @ casting? How about healing? Going pure HM% or so and high ee on main heal charm? Any comments on how a pure casting samurai has worked (someone who has tried it or has seen it in action).

they can be effective if you have good gear, but will the lack of mana they have it might be a challenge especially if you dont have a good tank in your catas and they other people don't kill fast enough

try to get armors with EE/mana

Okay, should I try to get %hm or int on my gear?

if you are just going to be healing, go HM

Just because you pass does not mean you have to play the next class. You can still choose magician again. However if you do this it means you cannot pass and you wlll be guarenteed 1gp only.