If you must have a laptop (desktops will give you much more bang for the buck), here are some general guidelines.
Monitor: You have to look at this thing. If you get a 10" mini and have to deal with 16 channels across the screen...you see the point. Aim for at least 15.6, but my 17 was a bit small for my taste. If you're adding an external, why not use a desktop?
Processor: In my experience, Intel chips work better for recording. There's a certain amount of bleed with AMDs when your video updates. i.e. you can hear through your monitors when you move the mouse....
Memory is not a huge factor in recording, but as always, more is better. If this is a dedicated machine for DAW, 4GB or better. If not, get 6 or 8 or even more, depending on whatever you need for other apps.
Drive. Most laptops do not have SSDs, but if you can afford the cost, hit a 480 gig or bigger for writing your data to. You can backup to externals when you get to a docking point. You really don't need SSD for recording, but they are nice.
Regular drives are perfectly acceptable to recording and even 5400 RPM drives are ok if you have good throughput. Again, larger is always better. Considering the cost difference, go with 3TB if you can find it.
Your device is USB, so that's not a problem.
Your OS is the only other problem. For recording, I always recommend staying back a step. XP is about to be lost to support, but 7 is still very stable. 8 may not be a great choice until there's a little time under its belt.
Hope there's some good info here for you. Happy Recording!