A few things you can do to make your life a bit easier for CCing with Seduction:
1. Download the FocusFrame addon over at
http://www.wowinterface.com/downloads/info6463-FocusFrame.html This will let you visibly see what target has focus as well as the Seduction debuff icon.
2. Make a macro for Seduction. A common one is something like:
#showtooltip
/clearfocus [modifier:alt]
/focus [target=focus,noexists]; [target=focus,dead]
/clearfocus [target=focus,help]
/petstay
/petfollow
/cast [pet:succubus,target=focus,exists,harm] Seduction; Seduction
When you click the macro on a target, the target gets focussed and seduced. You can then target something else and DPS away and just click the macro as needed to re-seduce the Focussed mob. Clicking the macro while holding ALT will let you switch Focus to a different target before your old one is dead if you need to. You can find alot of useful warlock macros over at
http://www.wowwiki.com/Useful_macros_for_warlocks
As for as the spell being channelled... In the WotLK Beta, the Improved Succubus 3/3 talent gives the Succubus a 100% chance to avoid interruption.