No alpha will be a complete wipe. The stated somewhere that BETA won't be a wipe, but right now things are changing quite a bit and they in major feature add and bug smashing. Once beta hits it'll be about tweaking and fixing but no massive functionality upgrades that would effect that the persistent universe. This is a skill based game btw, not a level based game. A good pilot in the starter ship is quite capable of killing someone in a hornet (the single seat military fighter), neither is going to do much to a capital ship. Some of the bigger mulitplayer ships would be extremely difficult for a single fighter to destroy if it has a crew. The thing about the multiplayer ships though is if you don't have a crew, you might get blown up anyway... actually you'll probably get blown up as they'd just run circles around you.
The great thing is this isn't Eve, where you just smash buttons while flying around each other. This is a dog fighter meets FPS meets space trucker meets pretty much what you choose for it to be. (cop, bounty hunter, pirate, marine, trader, miner, mechanic, gas station owner... yeah you can be a flying gas station if you want )
The only other thing to remember is that if you want to play the single player game at all, it'll be a separate purchase starting in February.
And this game strives for a certain amount of realism. Don't expect to take a small fighter up against a big ship that's got a good crew and think you'll win. It's like dingy going up against a cruiser. On the other hand grab a couple of friends and then kick his butt.
And you always have the option to fly around with worms and me, crew our ships with us etc. Between the two of us we got a good selection of ships and if we don't screw up too badly we'll make some money and you buy whatever ship you want . Also you can loan ships to people as well, so if we were running a cargo somewhere you could theoretically borrow one of our fighters to run escort. (you scratch my hornet and I'll kick your ass!)