Yes, fishing is a great 2nd if you know what is going on. Scroll through some of the past posts and you will see numerous postings about fishing and what it can do for you.
Somewhere on the forums there are several links that will explain a lot and are very helpful.
As far as what lvl, not sure as to the exact lvl but I was around 150+ when I started fishing trunks. When hit around 180+ could fish in floating wreckage. Lvling up in fishing is very easy you just have to dedicate a few mins every night and before you know it you will be up there. There are several +buffs that fishing suppliers carry that give anywhere from +5 to +75. So buy one and use if you want to be high enough to get the "money" fish. Spend a lot of time at the Oasis' in the Barrens. Really easy to lvl up there, plus there are plenty of nice things to catch to start.