Not necessarily, I can craft a majority of my tools and then farm the ingredients or trade what I farm for the ingredients I need (well, not lately but when I was leveling). At 75 a ninja with a sky shell can pretty much replace all that expensive gear with sky gear and quested gear and have a nice nest egg in the bank. I hq shihei and toolbag it(greatest change SE ever made). I farmed a lot when leveling ninja but I usually farmed for my ninja tools - I pretty much leveled Ninja to 75 for free except for armor that I sold back for a profit.
Ni wheel is the most effective hate holding tool from about level 40-65 especially with int and ninja af gear swaps for the spells. at level 50 a ninja should be outdamaging everyone and tanking quite fine. The damage of those spells then starts to taper off but it is still somewhat effective at 75.
Blind, slow, paralyze with gear swaps these usually stick and add a ton of hate. There should be no problems with Ninja holding hate from 40+ except a small window 70-74 where Monks are freaks and its tough to hold hate from them.