I don't know if it's been mentioned but you CAN upgrade the SSD drive in the new Airs:
https://www.macrumors.com/2010/10/27/256gb-ssd-upgrades-for-new-macbook-air-announced/
There's a huge difference between something being announced by an unknown company and being able to actually do it.
As for the thread question:
1.) Yes, you can use it as a primary.
2.) No, you probably don't want to do this unless you have to. Being your only computer is not the sweet spot for this machine. Pairing the 11.6" with an iMac though would be a great combination for power and portability.