Hi. I'm new to making plugins but I think I can make it. At the moment, I'm working on two beams: a point defense beam and a kill-everything-in-front-of-you beam. For the PD beam, it targets cap ships and when dominating planets, that's kinda annoying since they (the ships) don't disable. They also cause considerable lag. For the kill beam, the everpopular Megabeam Cannon, it won't prevent the firing of other weapons and isn't wide enough.

I'm not sure what's going on with your PD beam. Point defence weapons should not be able to target capital ships, unless you're also using a plug that changes every ship so that its "can be targetted by point defence" flag is set. Are you sure you have the right guidance type?

About the MegaDeath beam, you can try setting the CoronaFalloff to 1, which will make the beam about as wide as an Anaconda (although I think that only the center of the beam will do damage), or you can increase the Inaccuracy, which will make the thing fan out a bit (best done if it has a reload of 0), or you could combine the two.
To prevent other weapons from firing, set the "exclusive firing" flag. It may be necessary to give it a reload of 0. I'm not sure.

Edwards

Using EVNEW, for the PD beam, the guidance should be point defense beam, right?
I shouldn't have such a plug but the beams prefer caps to fighters and they don't target T-heads.

For my Megabeam cannon, I have the "can't fire until previous shot expires" and the "no other weapons can fire while this is firing" boxes checked.

I think you'll have to give it a long reload to prevent other weapons from firing. Other weapons will be able to fire whenever it reloads.