Which Amazon EC2 AMI to use for cross browser testing

Today Amazon released the news that they support 64-bit for m1.small instances, as well as the new m1.medium instances.

Read all about it:

http://aws.typepad.com/aws/2012/03/ec2-updates-new-instance-64-bit-bit-ubiquity-ssh-client.html

No, the small instances are 32-bit only while the large/extra large instances are 64-bit, so you need to use either the large, extra-large or high-CPU extra-large instances for a 64-bit system.

See the EC2 instance type list for more details on the different types.

Is this feasible/advisable?

Yes it is, totally, and it is pretty straightforward to implement. That's one of the big attraction with EC2 (and Infrastructure as a Service offerings) - you get to pay by the hour/resource instead of paying for hardware/networking up front.

We have licenses for the software we want to test with, but are there technical licensing issues with having the software (eg. QuickBooks) run once the image is restore?

Unless your license is for one machine and you don't run two instances of your AMI at once, you should be ok.

Any particular tools / scripts we should be aware of for helping with this? We're experienced on the linux side with EC2, but not on windows.

Not particularly. There's nothing odd about running Windows on EC2 when compared to running Linux outside of pricing, creating AMIs of instance-store backed instances (you have to use ec2-bundle-instance calls instead of ec2-create-image calls), and the usual differences between the OSs.