RAM, get 2G. You can never have too much RAM.
CPU, whatever. The N280 is a little faster, but I doubt it makes any real difference. You probably couldn't tell just using it.
Battery, get the bigger one if you plan to be without AC power for a long time. I've run about 2 hours on battery and OSX claimed I'd have about 2 more.
Wireless, the 15xx (wifi-N) card is apparently problematic. I don't have it, so I don't have details. The wifi-G card works fine for me though.
I don't know if the cell-internet thing works in OSX or not, I just use my cell phone via Bluetooth. I do suggest you get that if you think you might use it. It's easy to install later though. I also went with the 16G SSD
, but I don't need much space on this machine. OSX and all the apps I generally use take up about half of the drive. I wanted it for durability, having lost a HDD to a fall made me like the idea. It's also a pretty quick little thing compared to the 5400 rpm drives you usually see in these things.