Hi there, congrats on lvl 50 ^^

1. Yes you need cnj 34 (why not get the soulstone for WHM since he's gonna be over 30? ) to unlock Stoneskin on CNJ class, then you can freely use it with any other class, or specific jobs that has CNJ as available CC.

2. If you really plan on becoming a better tank, you will need MRD CC Skills. Fracture, Foresight, BloodBath, Mercy Stroke are the ones I use on my PLD, with Stoneskin.

The order of CC skills you will add on your CC bar makes a difference and are synced depending of the lvl you will be. So I always put Stoneskin first, it makes people very happy in Low-Level Dungeons

If you really want Cure, I would take out Foresight, since as PLD we have plenty of Defensive skills.
Keep it up, cheers!