Starting warrior, need some advice!

[Alpheus]

I tend to lean more to mage jobs but I can answer some of your questions. And sorry long post.

To the question regarding subjobs, Samurai is the subjob used the most by WARs as its job traits and abilities that you get from subbing it are very complimentary to WAR's needs. However early on WARs do tend to sub MNK until SAM is avilable. Just as long as you aren't subbing whm or blm you should be fine for GoV burns.

To the question about gear Pre lvl 75 nothing stands out minus mainstays like Hauby, AF1 feet and the like. You can totally get away with using a WAR equip guide on FFXIclopedia to give you some idea as to what you should aim for at various lvl intervals. The thing to keep in mind though especially if you are lvling using GoV, is that these intervals are shorter so you can skip certain pieces of equipment since the speed at which you lvl render them obsolete in a few lvls when something superior opens up. I would advise looking through such a guide and taking note as to what stays useful the longest and aim for those pieces of equips or their alternatives in order to save gil.

I would advise that as soon as you get to Jeuno ( as early as you zoning to Jeuno to get a choco license) you start the Abyssea Questline by talking to the Abyssea NPC in Port Jeuno and then continue on your way to 75+.

Once you are 75+ you are ready to lvl in Abyssea. In a exp party in Abyssea you are simply expected to do damage however that damage might not be much until you are situated quite a bit in Abyssea. Utilizing Atma combos allows you to deal greater and greater damage. Using atmas require you get Zone clears from each Abyssea zone as well as defeating the NM that provides you the atma. Acquisition of atma leads into the main role that WAR plays in Abyssea, red procs.

Proc'ing red on a NM grants you that NM's Key Item as well as their atma (if they have one to give) upon its defeat, Red procs also inflict the Terror Status Ailment on the NM for 30 seconds. Red Procs are by and large a WAR's job in Abyssea when you are on a Atma run or farming Key Items to pop some of the more harder NMs due in part to WAR's large repertoire of Weapon Skills which are used to proc red. As such, as a WAR you will be expected to have skilled up on weapons other than Great Axe to proc red on NMs. (Check FFXIclopedia for a full listing of WS procs by searching for the term "Weakness Targeting")

As for the gear you should aim for post 75 you cant go wrong w/ WAR Empryean Armor (AF3) you will want to aim for the +2 versions of each piece. Since you are a player starting over again I would strongly recommend you make getting this set your goal post 75. It is not the end all be all of WAR sets far from it, however it will see you through until such time that you do get far more rare pieces of gear should you so choose to do so.

NMs to note for Abyssea:
Briaeus- Megaboss for [A] La Theine Plateau
Glavoid- Megaboss for [A] Tahrongi Canyon
Kukulkan - Megaboss for [A] Konstacht Highlands
Cirein-Corin - MB for [A] Misareaux Coast
Itzpapalotl - MB for [A] Attowha Chasm
Sedna - MB for [A] Vunkerl Inlet
Resheph- MB for [A] Ulegrand Range
Bennu- MB for [A] Altepa Desert
Amphitrite- MB for [A] Grauberg

Other NMs to note:
Ironclad Pulverizer- Grants Atma of the Razed Ruins: Dex+50 Crit Hit Rate and Damage+30%
Bukhis- Grants Atma of the Sanguine Scythe:HP+20% Crit Dmg+30%
Eccentric Eve- grants Atma of the Voracious Violet: 2TP/tick Regain, STR+50 and Dbl Atk+10%

There are many more things to get done in Abyssea but I am simply providing you an overview. Best of luck in your endeavors.