You really need all classes to 50 for cross class skils, though leveling can be somewhat painless if you take ixal and gc turnins into account. Its somewhat slow but easy way to level. Only level the classes you really intend to use to 60 since there are no usefull skills past 50 in my opinion. (yes i know precise touch is somewhat essential but its common for all crafts)

Best for making gil is cul combined with a leveled botanist since it doesnt rely on any other crafter for ingredients. Alc requires both miner and botanist leveled to make a profit.