Be sure to use an EBS-based root volume. http://developer.amazonwebservices.com/connect/message.jspa?...
If you don't, you have to be extremely careful to avoid losing data.
If you have questions or concerns, don't expect service of the same level as slicehost or linode. AWS serve much bigger fish than you, folks using hundreds of instances. It's not a criticism of EC2; I still use them. Just be aware of the trade-offs. It's cheaper because there are certain things you don't get.
Yes. I know several people with EC2 instance uptimes well in excess of that.
Out of curiosity, why would you want to move from a host that is providing you just that? I understand price may also be a factor, but that is a rather large jump in resources, which leads me to believe it's overkill.
We've tested from different geographic locations and the issue remains. It's been like that for about a month now.