Greetings Domanting.....
I'll try my best to describe the myriad of options present in the scheme editor....
Activation By:
Crosshair = Bazooka/Mortars/Nades.....etc
Throw = Dynamite/Mad Cows/Old Womans....etc
Airstrike = Airstrikes
Space Bar = Utilities
The Subtype affects various things depending on the number, for instance....switching the subtype of bazooka to "10" (which is what longbow is set to) will make the bazooka only aim 45 degrees...like longbow. It's more important with guns as the subtype also controls what animation is displayed when firing (assuming yor not using your own custom animations). It comes in handy when creating custom guns as you can mix and match the sounds which is pretty cool. It's a setting that aloows you to "hybridize" your weps and really the only way to get a sense of it is to test it out.
Herding is used for weps like Mad Cows...."1" is default value for setting the ability to throw "x" amount of "cows".
The "Unknown" fields in the "Bouncing" tab are something I never really figured out 100%....I'm pretty sure it affects bouncing force when the wep is set to explode on anything it collides with like a pinball exploding on every suface it hits....again it's hard to say...I remember having to tweak it for magic slammer so it's something along these lines but again I could be very much wrong.
The "Unknown" field in the "Explosion" Tab has something to do with weather a wep explodes after using up all its pre-defined bounces.....I think.....this one stumped me...the editor auto-assigns this field with a 1 if you tweak certain bounce settings so it's related to boucning in some way if your wep has "x" amount of bounces set to it before it explodes.
The unknown field in the "Roaming" Tab controls a roaming wep's (cow/sheep)...ability to walk up steep slopes before jumping.....the higher the value the more likely the wep is to traverse up steeper inclines without jumping....I'm pretty sure I have this correct but I might be a tad away from it's true purpose...
The "???" box in the "Explosion" and "Bouncing" Tab controls weather a sprite is displayed when a wep collides with anything...check this in the bouncing section for "grenade" and toss one and you will immediatly see its function...It's a cool effect.
"Explosion Bias" is a very handy setting for shifting the explosion upwards or downwards on the x plane....a higher value will displace the explosion downward.....This page gives a nice idea of how traditional WA uses this feature...
http://worms2d.info/Explosion_BiasHaving the bazooka perform a "spreadshot" is impossible without scripting the game which is something I never really became proficient with.....Pyroman did design a bazooka that shoots twice in rapid succession but having it explode into clusters and then having the clusters also follow the original trajectory of the bazooka is also impossible without scripting...you could make the clusters "homing" and it would be somewhat of what you were trying to accomplish but ya.....I could create the bazooka that shoots 3 times for you but it would be one after the other and not like Super Contra by any means.
I hope this info helps.....I guarantee the more you fiddle around with things the better you'll grasp whats goin on.