1. You have to get promoted to a certain grand company rank to be able to buy a chocobo... and then it just cost company seals to get it...
The actual company quests reward seals so if you're just starting out in a company... by the time you get to the rank where you can purchase a chocobo, you should have enough seals if you haven't purchased anything else
It is worth noting that Chocobo and Goobue are the same speed... I don't know if that changes your priority list for obtaining one... I prefer chocobo just because Im a fan....

2. Leves are a great way to level... but much more so at the higher levels. Leves give a very nice bonus in XP at the end... and the higher leves give a bigger bonus. Also, completing the leves in 25% of the time allotted (Usually in under 7.5 minutes) nets you a bonus XP reward for speed completion.
It really depends on your level and moral stance on power leveling. XP parties are a great way to go at any rank. Forming them and then deciding where to go can be a bit much if you are unfamiliar with the world and where MOBs group at. I love beast encampments though. They tend to have a very tight grouping of MOBs that respawn fast and are fun to kill. Also there are encampments in tons of different level ranges. Also, many quests (Main scenario, class quest) give XP, but they are far and few between. But if you have any available... I'd do them

3. Materia is viable... but even then, its only at the cap. I take that back... kind of...
If you had a random Tier II or III materia laying around... I'd throw it on a Level 30+ weapon or armor just for the boost... Its not necessary and I wouldn't invest any time into it before cap... but if its there.. why not...
As far as Materia at cap... yes.. it is very nice.. but certain materia have become more valuable than others...
There is Unique untradeable gear that can't have materia... but having a level 50 crafted gear with 2 materia is just the bees knees. For weapons though.. because Base damage is so broken... for a melee class you want a Primal weapon.. no question

4. Websites
Mooglebox.com has the best filtered search
Mozk-tabetai.com has some good info and is best for quickly looking up an item by category..

Like if you wanted to quickly see all 2 handed thaum weapons.. Mozk
But if you wanted to sort thaum weapons by which one had the most Int... Mooglebox

Also I like FFXIVmaps.com for.. well.. obviously maps

Disciplesoftheland.com for gathering info

XIVpads.com for tracking your characters development and seeing how fast you're leveling...
planning your characters growth...
setting personal goals for your character....
seeing what you're missing in game in terms of achievements and quests...
keeping track of NMs you killed or have yet to kill...
which aetherytes you've touched...
very useful site. Also the chatbox there is a great way to find other external resources... Viion has a bunch of cool links and such... thats actually where he put me on to Mozk

Lastly... for the attributes.. they make it so you can't put it all into 1 stat
For Conj, I'd dump as much as you can into mind (For healing) and the rest Piety (For MP) although the case could be made that Vitality is also an important secondary stat (For enhancing magic potency)
But definitely as many points should go into mind as possible