Hi Rudinho, thanks for the feedback. Mind if I add my thoughts on the matter?
1. Are you reading those damage stats from the in-game Encyclopedia? Those damage stats are reported wrong because of weird math functions (hardcoded afaik) so dont rely on them for reference.
Check the first post in this thread for a downloadable spreadsheet with the proper stats.
AFA does 3000 shield damage per hit
ESR does 1250 shield damage per hit
Over time the AFA does 180% x damage of ESR
A couple of AFA on the sides of a cerberus is enough to tackle khaak swarms and pirate patrols quickly. Mounted in 4x batteries on a Colossus, AFA is an impenetrable anti fighter screen. Is a measured choice, cig is good bug zapper for m5/m4, AFA is choice for more damage, both are very accurate as the AFA has a rapidbox of 25x25, which is as close to a flak area effect/proximity detonation you can get in X3.
Flak and Frag effects are purely cosmetic unfortunately. They have no collision mesh and are useless except as eye candy, flak weapons are little more than fast lasers with flashy effects. I'll look at the flak stats again, but keep in mind that players also have to go up against flak, so cannot be too powerful.
2. Nothing I can do about the M7 tiger turret problem, fingers crossed for a cockpits fix in XTC eh?
3. Gauss weapons
are low tech

They shoot lumps of metal through magnets with an electric current, you can build one in your backyard from household goods that'll punch through car doors. Sounds pretty low tech compared to High Energy Plasma Throwers.
I modelled the Cmod3 gauss cannon on the American military prototype gauss weapon they'll be fitting onto naval cruisers after 2012, the projectiles go so fast they ignite the air they pass through. Just because it's low tech doesn't mean it can't be badass.
http://www.youtube.com/watch?v=i1q_rRicAwI
At the present moment Gauss does about 2/3 the damage of PPC and is limited by ammo, cargo and supply constraints (25 T. per 200 rounds, limited supply in current economy).
Now I've said all that, I'll take a close look at the stats with your suggestions and see if anything can be added.