I don't understand your question entirely because there are a lot of questions I would like the answer of from your question but here i'll explain the basics.

Once you get your 2nd job (gladiator to paladin) in my case; The stats would increase by a substancial amount. Equiping Armour/Jewellery which Vit + 2 gives you 2 extra points to your vitality, same goes for all the other stats, assuming you had them in armour/jewellery slots. In my opinion you should un-equip everything in a main town like ul'dah, limsa lominsa or gridania. Same where safe and not in sanctuary. Then equip one item at a time and see what it does. If you chose not to then you have simply wasted your time asking the question in the first place.

Apologies for my grammer, it's quite late here. so tired. lol.