Yeah, more planets are generally better than (very) well developed planets for most of the game. Also, it sounds like you just need to get more familiar with the game so you can make your opening moves faster. Try playing the game without any AIs so you can practice expansion without harassment, or watch some replays of experienced players to see what you need to do.

I think static defenses are a completely different ballgame depending on whether you're playing AI or another human.  Humans can just bypass it, so your statics just aren't defending that much.  The AI--well--not so good.  What I really like about statics vs. AI is, no fleet logistics.  If you've got 5 planets in a row and 2 choke points on either end, you can turtle up one end and station your offensive fleet on the other.  If the AI had the sense at all to send 5 siege frigates right around your turrets and bombard the planet behind it, that would be a different story.  But that doesn't happen.  I'm also killing an AI cap ship with a starbase almost every game.  vs. Human, that's just not going to happen.

I'm beating Hard AI every time now, and moved up to 4-player FFA.  About time I graduated to Unfair--I just want to make sure I'm beating every Hard AI handily, on every map.  Maps with no chokepoints and no Dead Asteroids are the hardest (the AI's defend their dead asteroids to the death.  They're also very kind about exploring it for artifacts on my behalf).