Same with BB10. You just hit delete for the ones you want to delete. Done. You don't even need to select them first....then touch delete (to delete all selected), because you're already done. It's actually faster as it requires less touches than what you just described. If you delete something you didn't want...you have a few moments to undo it.
Asked and answered already; because you don't accidentally hit "send" before you are ready to send. Just like on many other platforms or clients. I'm sure there are a lot of WP people complaining how "stupid" it is that the send button is so close to all the other keys they are using to compose the message. But if you have a classic (oh, those sweet buttons) your problem is solved again. Just two squeezes of the menu button and away it goes. First squeeze brings up menu with Send highlighted, and second squeeze actually selects the highlighted "send" action which then sends it. Super fast and efficient, and very had to accidentally send a message before you are ready.