Is your version of sins fully updated? You will need to download and install impulse to update sins.

Visit http://www.impulsedriven.com/

Just so you know, Impulse is Stardock's version of Steam and you'll need to register your game's CD-key in order to update it.  This is the only form of DRM the game has, which isn't at all bad.  Impulse is very benign and you don't need to run it in order to play the game--only for the occassional patch.  It's great that you want to come play the game in online multiplayer; it's really a great game.

upgrading the fleet capacity is similar to researching a certain tech, so, as long as you can pay for it, you can always do it.

the only drawback is that it will permanently cut your income by a certain (rising) percentage and is not again "downgradable", so yes, in a certain way, you´ll have to take over more planets first to avoid an economic crisis

thnx for answering my fleet question, but im still having trouble with logining in to ironclad. I couldn't find a tab on impulse that says upgrade on it. Also When you start the program, and it pulls up the menu you click on the ironclad online tab and not the multiplayer tab right?