Together from the start..

[Rongway]

1.) can we got same story quest or just quest if we on the different class on level 1 ?

Each starting city is home to certain classes' guilds. If you and your wife choose classes that begin in the same city, then yes; however, if you start as classes from different cities, you will be separated until between about Lv15.

Here are the cities and their classes:

Limsa Lominsa
====
Arcanist (ACN) - Caster, becomes Scholar(healer) and Summoner(caster) at Lv30.
Marauder (MRD) - Tank, becomes Warrior.
Rogue (ROG) - Melee dexterity DD, becomes Ninja. Not available as a starting class.


Ul'dah
====
Gladiator (GLA) - Tank, becomes Paladin.
Pugilist (PGL) - Melee strength DD, becomes Monk.
Thaumaturge (THM) - Caster, becomes Black Mage.


Gridania
====
Archer (ARC) - Ranged DD, becomes Bard
Conjurer (CNJ) - Healer, becomes White Mage.
Lancer (LNC) - Melee strength DD, becomes Dragoon



So if you want to play together starting as a tank and DD, you could be MRD+ACN so you both start in Lominsa, or GLA+THM so you both start in Ul'dah. Or if one of you wants to heal, you can CNJ+LNC so you start in Gridania. Unfortunately, there is not currently a combination that would allow you to play together as a tank and healer right away.


That said, getting to Lv15 and being able to travel to the other cities comes pretty quick, so if you have to compromise on a class combination to start, it won't be long before you've advanced the story to where you can unlock a class that you actually want to play.

Or if you start in two different cities, you'll find the stories converging around Lv15, which is when you'll be able to meet up and continue together.

2.) what happen if I just playing to lv.50 and not taking a job?

Classes after reaching Lv30 aren't a real thing. The jobs are uprades with higher stats and specialized abilities that make you much better at your role. Currently, they require the base class at 30 and a supporting class at 15; however, beginning with Stormblood, the support class requirement will be abolished.

3.) is the equip is different conjurer/archanist and white mage?

A White Mage is a Conjurer. It can wear anything that a Conjurer can wear. Arcanist is a damage dealer. Healer and magic DD gear is the same at the beginning, but after 30 the gear sets start to become distinct from each other.

Scholar and Summoner are both Arcanists, and will be able to wear arcanist gear, but at later levels they will be wearing role-specific gear because SCH's main stat is mind while SMN's main stat is intelligence.

4.) if I was dragoon and decide to be black mage, I start from level 1 again as thaumaturge ?

This is correct. The classes begin at Lv1, and then jobs unlock once the appropriate base class is Lv30.

Heavensward jobs will require reaching Lv50, completing the 2.55 story, and entering the first Heavensward area. Once unlocked, they start as jobs outright, as Lv30.

Stormblood jobs will require reaching Lv50 and completing the 2.0 story, and will be available somewhere in a Realm Reborn area. They will start as jobs outright, as Lv50.

5.)to be a dragoon I sud have a lancer lv 30 and marauder lv 15. what happen my if lancer was lv 50 and marauder lv 50??

Dragoon is a lancer, so you would be a Lv50 dragoon.