the best thing u can do to learn is to watch a few replays u will find some here

Regarding defences... the best thing is to build em very close to ur planet/asteroid.
The main thing u need to protect is ur planet health/population. Thats why u should build ur other stuff also very close to the planet.
I always place my turrets in the direction where i expect the attack from. Ofc u have to spread them a bit around ur planet so that the enemies just cant fly around and attack ur planet from a different side.

Will those replays still work on the release version? I'm planning on preordering with tokens, but by the time my cheque comes in the game will only be 4 days away and seems kind of pointless to download beta 4 for just 4 days.

the best defense is a good offense   . I'm serious, if you even send a small offensive deep into enemy territory he is going to be forced to withdraw troops from at least one other place, and if he's overdedicated to your front line than thats where he'll probably pull from.

if he doesnt then you've just got a free lunch pall, chow down.

My way of defense is a more of an 'offensive defense' that I start planning during the colonization phase. Try not to expand in a straight line, as more often then not, it will leave most of your planets open to attack. If you expand around your homeplanet, there will often be less planets to defend.(say there are three planets one jump away, you colonize them all, you will only have to defend those three, instead of four). This is even better if one or more of your planets only have one jumplane for you can hopefully colonize that gravity well leaving you with another planet under your belt without another one to defend. Once you have enough planets/enough to defend.

With that, all you have to do it fortify the frontline with defences (missile turrets in my case ) and some ships. That way, you can push yourself forward if needed without losing much defence (take one of the frontline planet's defence, move it forward and attack the next grav well). I haven't been able to play long enough to get to the gate tech. With that, you should be able to have gates at all the frontline planets allowing you to have one defense fleet (maybe two incase of a two prong attack).

BUUUUUT! I am still just a complete noob at this game, and I have no idea if this would be any good online.

Hangars tend to be very powerful defensive tools. Fact is, you really can't just "cover" a planet with a lot of turrets -- you run out of logistics points -- so what I generally do (I play TEC ) is place hangars, guarded by repair centers and turrets, and force the enemy to come to me that way. Planetary shields make bombardment take forever in the late game.

Thanks guys, I more meant if you wanted to defend that particular position. I understand attacking would alleviate the need to defend. And so from what ive gathered you center your defences on hangers with turrets and repair bays surrouding them and the hangars are based real close to the planet? and the hangers reduce the need to have a planet wide defence? Do the hangers provide enough of force of fighters n bombers that the enemy needs to confront it? Thanks for any answers even if it seems obvious

Custom maps?  Nope.

As we warned, expect any mods that have been done thus far to be broken in the release version. On the bright side, it'll be much easier to re-create custom maps.