After so long I decided to play this

I love FF in general, played a lot of them since PS1 days but never had my hands in Tactics before. I started playing in my old ass GBA so I have a few questions please:

1. Is it advisable to train a few more people other than your main party for dispatch missions?
2. Is the other class more stronger than its pre class job? (eg. Sniper?)
3. Is the steam port better than the GBA in terms of content or is it the same? I am enjoying my time in GBA but I was wondering if there is more in steam.