At this point, I have two issues.
1. This party is, in my opinion, a little light on heavy melee PCs. You have a barbarian (new build, defender striker class), a bard, an assassin, a CON-based warlock, and a psion. If it were me, I would seriously consider having somebody take a Defender multi-class feat or something like that that enables you to mark something or just go a little heavier for those times when that's appropriate. For example, the Paladin multiclass feat enables you to use Divine Challenge once/encounter. The Swordmage multi-class feat enables you to increase your AC via Swordmage Warding for an entire encounter once/day. It's up to you, of course, but I fear your "squishies" are gonna get squished.
2. The other potential solution to this problem is to invite a 6th Player. The upside of having 6 is that when someone inevitably disappears, we'll still be set with 5. This is the main-most reason I'm considering it.
The downsides of 6 PCs are twofold: 1) the encounters are a little slower and more drawn out. 2) The game is naturally balanced for a party of 4 or 5. Having a 6th PC changes the dynamic quite a bit, resulting in, well, more work for your ever-lovin' GM. At Sellswords, we've played with both several times, and I think we all agree that the game runs a little better with 5.
Lastly, this game is starting at 2nd Level for story reasons, but I plan to give out double XP initially, and more to the point, I think the game is basically more fun when you have a nice selection of Encounter powers. So you'll advance quickly. We may even skip whole levels. Hell, I've been mulling over the idea of skipping the Paragon Tier in its entirety and vaulting straight to Epic once we get through my initial story ideas.
So. I have to draw a few maps and otherwise finish setting up the first encounter set. If you'd like a homework assignment to keep you busy and get a feel for each other, I can do that. Otherwise, please talk amongst yourselves and finish designing your characters.
Thanks. And welcome aboard.