@ VSLN
1) I love SPAZ too, I found this game on a blog talking about SPAZ. Lucky.
2) Starting out in the campaign can be hard, or kinda easy, and it's mostly luck that decides that. What I do is start a new game until I get the starting ship I want (wolf class or lasher). Then I hunt small pirate fleets, either single ship or 2-4 ships/fighters. Take the enemies one at a time and try to minimize damage even if you have to pull back. Damage is a killer in the long run. So I do that for 10+ fights and by now you should have captured a fighter/frigate to add to your fleet. Importantly, adding ships to your fleet slows you down a lot. Sometimes it's best to immediately sell all the ships you capture, if they are damaged when you sell them, they tend to stay cheap in the store, so you can buy them later when you can afford the slower fleet. When you have about 30k credits and or lots of cargo (did I mention you don't need to stay in the limits for cargo/fuel/crew? No penalty at this time), go to the station and buy the Hyperion. Try and get a Hyperion + Tempest OR Wolf(with engine aug). Those two generally make a speedy and deadly combo. By now you can take on the medium sized pirates (carrier groups) and mop up after larger fleets class. Go ahead and aggro the Independents if you get a chance, but stay away from the advanced multi cruiser fleets, they will mess you up. At this point I don't recommend *** off the Tri-tach or Hegemony (blue/brown). Continue on from here for a bit until you can afford a Medusa Cruiser, at which point you should be able to take on some serious fleets with the Medusa + Hyperion + Tempest +misc fighter/bombers. You can also dominate any fleet smaller than yours.
3)When you have a small fleet (3-4 ships or less) you generally don't get the option to deploy. Rather you just get thrust into battle with your whole fleet and the enemies whole fleet. Rarely are there goals on the map to capture. This changes when you + your enemy have more than a handful of ships between you. I'm not certain the exact limit.
4) There are 3 sizes and 4 types of slots. They are Energy (blue circle for small, 2 circles for medium, 3 for large). Ballistic (Yellow square for small, etc). Missile (green square for small, 2 squares for medium, etc). And Universal (grey Squares).
Pirates don't have the best equipment. As to that, head over the mods section and find the Tri-Tachyon Station mod. It puts a blue station near an outer planet that works like the brown Hegemony station, but it sells mostly high tech ships and energy weapons. Highly recommended. (Btw, can't remember who made it, too lazy to look, but you rock)
And a few more little tips: In frigates and other small ships it's often worth while to Hold down shift key, press A or D to side slip, and while you hold shift down, your ship will aim at your mouse. It sounds dumb the way I describe it but it's a FAR better aiming system than using A,D to turn. I'm hoping for a toggle button on this mode later on.
Use Autofire (shift+weapongroupnumber (such as 1, 2 whatever)). Any weapon you aren't controlling yourself should on autofire, especcialy turrets. Exceptions for missiles and other limited ammo weapons of course. You can also press X to hold fire, it's a toggle, so it stops all your auto fire weapons until you press it again.
About the capture mechanic at the end of a fight. If you disable a ship in combat you have a roughly 10% chance (maybe less) of it being capturable after the fight. You then can mouse over it to see how much crew it has left. 1 crew, no problem. 10, sure, try it. 40, maybe you don't have that many marines, yet. If it has too many crew for your marines (figure 2:1 marine:crew is good) then you can scrap it instead. Further, in bigger fights, you'll eventually engage and the enemy will try to escape. When this happens you can often have ships surrender to you after the fight is over (only if you win). These ships that are marked (surrendered) do not put up a fight when you board them, and take no marines (you need to have SOME) to capture. You can read more details about this mechanic in the forums.