Originally Posted by Zegridathes
2. Is it possible/advisable to max out all the skills in one class before switching to another? Can you get by maxing out one skill in a class for the skill tree effect (provided they don't offer different effects) and leaving other useful skills at less than five?
Possible? Yes. Advisable? Probably not, depending on your class. Generally speaking, there is at least one skill in a class that isn't all that useful and you'd do better by switching classes earlier and getting something from another class. e.g. in my case I went sorcerer -> wizard when I noticed how little anti-boss and bullet removal abilities I had.
Strictly speaking though, if you have a fighter friend who you regularly stage with, you can pretty much get by with anything as long as there is enough mob control between the two of you.