Hi,
you can use BuddyPress in the plugin name, under condition the public can understand clearly that it is an add-on FOR BP and not a part OF BP.
For the domain name, i presume it’s the same trademark condition as for wordpress: no, you can’t. You can use bp-something[dot]com but not buddypress-something[dot]com
BuddyPress comes like WordPress under GPLv2 license and has similar terms of use.
Here’s an example of what’s allowed:
Activity Stream Plus for BuddyPress
Note, the following is an example of what isn’t allowed:
BuddyPress Activity Stream Plus
You may come across older plugins that use the 2nd naming style. That’s because the guidance above was introduced by the WordPress Plugin Review Team relatively recently.