Updates past that initial CD are liable to be a different story.
That said, the activation will generate a code you can email to have it activated on other machines. And once it's activated, so long as you have the sig.bin for that machine (and don't reinstall your OS), you're set.
If you want the game on your home machine, your work machine, the laptop, the tablet pc, and the PC you're "storing" at your cousin's house, nothing's going to say "BOO". When your serial is on a webpage and 25 different email addresses are trying to use it to register that aren't you... they're going to be somewhat disappointed.
Please remember we are users of our own software and the activation was developed in such a manner that we are comfortable with it. Incidents like this week aside where it was available in a game beta on a wider-scale aside, but that's what time and testing are for. All previous activation bits were from their first builds, rather than added later. Missed a whole little assumption about when to check for the activation and redo it seamlessly there.
Your #3 problem above was an issue with the builds on Wednesday, it's sorted now.