So what's the stupid question? :biggrin:
Personaly I use a Buddy SMB which is self sealing, costs a little more BUT doesn't deflate at the surface. I also have a good reel, a full size one which can be used to hang off during stops if required, I know boyancy and all that but.... :spank:
I dive with some one who swears by a Buddy with auto air inflator, but the downside of that is if it failed there's no way to manually inflate so you need a backup, which defeats the object.
Regards practice...
Depending on depth, sink to the bottom dump all your air from BC and/or suit. One deploy the DSMB holding the reel the other inflate, feel the tug and let the release go. DO NOT fasten to your BC as my mate did (very funny) and he was showing me
Both have a go and then surface. Simple