1) Battle regimens are a joke now due to only 8 people being in a party. They shined when you had 15 people and 8 solid dps could stack to hit 2-3k Quick Knocks and Chaos Thrusts on the 8th slot. They are also being removed completely soon.

2) If you want the most accurate prices check the wards. YG for recipes is still good but almost all of the recipes in the game are being changed in 1.19. The Economy is super inflated due to no gil sinks but it's extremely easy to make gil so it shouldn't bother you too much.

3) Stats have not yet been redone. Look for that in 1.19.

4) I own 1 set of gear for each class atm that play off that classes strengths. Stats are still broken and there isn't enough content for multiple/different sets to matter at the moment. You should always stick with the "optimal" gear closest to your level because the further you are away from that optimization, the faster your gear will degrade.