HN user
(Another ex Heroku person here)
At the time of acquisiton (Dec 2010) the Bamboo stack was the only GA stack, Cedar was in beta which used buildpacks internally but custom buildpacks didn't come to 2012 https://blog.heroku.com/buildpacks
The press releases talk about them not being Safe Harbour yet but it is now much more in progress. Your data may pass through the US still at presently.
I'd add:
3) Tmux sessions are restricted to the size of the smallest client connected to the session. We've recently started using it at work and it works fine for 2 of us, but 2 others found that the resolution differences between their 13" and 15" macbooks means that the 13" sets the tmux session size so the 15" doesn't use the whole screen.
If a Heroku application's DNS is setup correctly then you can usually avoid problems like this on the new Heroku stack (CEDAR). It's important to reread the documentation on using custom domains but also be VERY aware of using naked domains (mysite.com) in your application. This isn't just a Heroku problem, it's a DNS problem. Heroku have recently had a spate of routing issues (usually DDoS attacks) which would have been largely negated by correct DNS setup and either avoiding naked domains or using a DNS host that lets you cname a naked domain to a host.