If you're fishing with mono, you should change your line regularly, at least twice a season.
Spend $25 on a Berkley manual line winder.
http://www.cabelas.com/cabelas/en/te...&cm_ite=srchdx
Also, spend a little more on the premium monofilament lines.
Berkley Big Game is good, as well as Ande and Sufix Tritanium. For the spinning rod, *stay away* from the Yo-zuri hybrid.
For the kind of fishing you're doing, I would go with 25 lb. test monofilament but no heavier.
As far as connecting main line to leader (you should be using a leader, whether it is a wire leader or a monofilament or flurocarbon leader), the easiest thing to do is use a 100 lb. test barrel swivel. Both ends can be tied with a Uni-Knot.