Too many people focus on caps.  I would say focus only the caps that will become very dangerous, like a rampaging egg or marza nearing lvl 6, or a sova thats doing embargo on your homeworld.  Otherwise only target caps if your damage type is not optimal vs the enemy frigates.  Like if you have ton of LRMs but enemy is all flak, take his cap out and probably retreat afterwards. Biggest mistake people make is leave their fleet in play because they think they are winning after they killed a cap.  While the enemy might have a fleet of Heavy Cruisers in play vs their LRM+Flak.

Also if you plan on killing a cap better make sure it doesn't get away.

Massing Cobalts is a bad idea.  Massing Javelis LRMs is significantly better, of course a balanced fleet of light carriers, heavy cruisers, LRM, and flak is best.  If you're facing massed Disciple vessels, mass LRM.  They are the direct counter to light frigates which is the category under which Disciples fall.

Capitals are generally bad targets early on.  That said, if you're facing a Vasari Evacuator or a Marza Dreadnought that is getting close to level 6, you'll want to focus on them.  Later in the game when capital abilities really start augmenting fleets, focusing fire on a capital is a much better idea than early game when your DPS is significantly lower.

I also come from te SC and SC2 community, and i find in this game that the ratios are much more important then in SC/2. And static defence sucks in sins.

Static defenses are primarily anti-rebel/anti-pirate, though you should never underestimate them.  The addition of shields from Advent hangars for instance drastically increases survivability.  Repair platforms are great assistance for fleets when on the defensive and AM recharge structures and weapon jammers can also come in very handy.

It's primarily that they just need a fleet for assistance.

Static defense is useful when the enemy has to face you at the static defense point.  Static defense simply gives you more firepower / credit than any frigate.  Yes some might say the enemy can go around them, but that is not possible in all cases.  And of course repair platforms are a must.