You MUST choose Federation first Xeno. You unlock your second free char slot at 24, and that char must be Klingon Empire. Additional char slots bought can be either Fed or Klingon (if KDF is unlocked).
Also, what you need to know is that your Class and your Ship do not have a major influence on each other. Your Class is first and foremost what you do on Ground when you apply your Kit, which is essentially your special abilities (Tactical = DPS, Engineer = Summoner DPS/Summoner-Tank, Science = Debuffer/Healer-Tank, that's the short of it). In Space, what matters more than anything are two things: Your Ship (Escort = DPS, Cruiser = Tank, Science Vessel = Buffer-Debuffer), and your Bridge Officers (who will be your array of special abilities). Space Skills are identical for all Classes (though only a specific class unlocks new training options for Bridge Officer abilities due to skill levels, ie only Science captains can teach Hazard Emitters III and only Tactical captains can teach Overload Beam III; Otherwise you need to either buy the abilities or use a non-commisioned Bridge Officer to teach one of their abilities).
But the most important thing to do is list your char and username here so someone can send you an invite to our chat channel, ImmateriumChat.
I know about the free ships, but many stay locked until you buy the credits, no matter what your rank is. I haven't been playing that long (only level 10 now) but still.. I think the Excelsior class and that bad-ass looking Galaxy Class with the extra nacelle are some examples. Same with the TOS Constitution class (not that anyone would want that hunk o' junk).
Those things are Premium ships, actually. Like Premium races, they are the meat of the revenue for Cryptic.
And screw you buddy, I bought the TOS Constitution. There's a kicker in buying it too as well: It gives you Rare front and aft phaser banks THAT SCALE WITH YOUR LEVEL (= awesome).
The game plays very fast and loose with the Star Trek canon obviously but it's still fun. Only thing I have a major problem with is all the different currencies. The Federation is supposed to use no currency, not fucking 4 types. Actually I heard it used to be 7 before they merged some into Dilithium. That and the random disconnects/crashes or bugs like warping into a system with nothing in it. But from what I've read the ground missions have been improved and the Duty Officer system is completely new. That would certainly change the game a lot.
The way I see it, Energy Credits reflect other resources you have at your disposal, like power to run replicators and so forth. As far as I know, Gold-plated Latinum is a space jew thing, and it's actually not a primary currency but more of a token system. Dilithium is fairly obvious.
Also, I'm the only one "sort of subscribed", which is why we have our own private chat channel. Being a Lifer in Champions gives me that right forever and ever, and the private chat channel exists on both Champions and STO (yes, we can talk across different games with it).