Sup man?
In answer to question 1) - It depends!! its kinda confusing to explain!
basically your mixer will be the deciding factor, if your mixer has balanced inputs, and your other equipment that you are going to route into the mixer has balanced outputs! then it is advisable to used balanced cables to connect the two! since one will have a balanced output and the other a balanced input, then the balanced connection will remain from start to finish, delivering a high quality audio signal!
However..........if your mixer has UNBALANCED inputs, then regardless of what you hook up to it (either balanced or unbalanced cables) the connection will remain of a lesser quality because the end of the signal path, your mixers inputs, are unbalanced!
Put simply -
Unbalanced ouput to Balanced input = Unbalanced connection
Unbalanced output to Unbalanced input = Unbalanced connection
Balanced output to Unbalanced Input = Unbalanced connection
Balanced ouput to Balanced Input = Balanced connection
There are also Inputs that accept both Unbalanced and Balanced Signals from a variety of sources!
In answer to Question 2) a 1/4 inch Jack is a quarter inch 1/4 at the end o the day! however, quality does vary with different brands and designs of cable!
i recommend Nuetrik connectors!
"It takes a bigger man to squash a fight than to set one off, knowledge, i let some off"
-Guru