Thanks a lot for the answers!
1. Can you tell me approximately how many unique visitors you had during the shows? I'm kind of curious...
3. We're using cloudfront... So you'd advise on using Akamai instead? or would cloudfront be ok?
6. For payments, we're using Authorize.net (with the CIM feature to capture credit card information)... Hadn't thought that they could be a bottle neck but I'll definitely at least check up with them...
7. Makes sense, I'll suggest that...
It'll be a fun few months preparing... I've been meaning to play around with Varnish, now's my chance :-)