Plg development: used versions of vm, plugin, joomla

[Tretwen]

Hey all,
three short questions and I hope someone can help me:

- How can I get the used VirtueMart version from within a VM plugin?
- Is a plugin version also somewhere defined expect of its own xml definition? Like in a database table?
- How can I get the used Joomla version from within a VM plugin?

Why I'm so obsessed with versions? Well, I need to send these versions
due to support reasons from my plugin to an external interface.

Thx & greetings, Tretwen