Can I use banshee from the command line?

According to man banshee, it is possible to control playback. I'm not sure about searching though.

Here are a few of the controls that you mentioned. Check the man page for many more.

--next 
    Play the next track, optionally restarting if the 'restart' value is set

--previous 
    Play the previous track, optionally restarting if the 'restart value is set

--stop 
    Completely stop playback

--play 
    Start playback

/usr/bin/banshee --next
/usr/bin/banshee --previous
/usr/bin/banshee --stop
/usr/bin/banshee --play

All those above can be used in XFCE for shortcuts on your keyboard, respectively for:

X86AudioNext
X86AudioPrev
X86AudioStop
X86AudioPlay

If you're looking to program an interface for Banshee (Other than just having the ability to send banshee --next or other control flag. Then you may be interested in the MPD - The Music Player Daemon which allows you to create your own interface or modify/use one of these Clients designed to work over MPD