Hi there!
Some quick answers here.
Line snapping.. mostly this is luck/unluck thing. Bigger fishes snap line more easily. Pike has the sharpest teeth, but also some other species can cut the line. Now you have only 1 rod to use, which is quite light set for pike fishing, which means also many lost lures in areas full of pikes. In 0.7 there is new rod available, which has stronger line. It will help you a little bit with "average sized pikes".
+ and - symbols wont do anything with fish handling now.. these are planned to be as a indicators of temperature.. If player gets cold, then movements are slow (detaching fish, inserting maggot etc takes more time). And when its too hot, then your character cant run anymore etc etc.. +/- are used in this kind of situations, like "+" at cold and windy day makes your character to wear mittens etc etc etc etc.. It will be available later.
Jigging.. there are lots of ways to do it. Too much movements (too large, too frequent) gives a "scare effect" to fishes. Ideal movements attracts fishes from distances. Rare movements have lower effects. But in crowd these normal things are not the same anymore. ..and everything depends on the lure you are using. Their weight and size has a large effect with jigging style also. I will not give you detailed information, but maybe other players have some experiences to tell you.
