For 1, the short answer is you want your rogue to either get some CC or secure a way for you to CC without getting interrupted, and then attack the kill target with a stun so that you can 2v1 them and put them in a check situation that they need to answer with major cooldowns.
How do you do that depends strongly on the comp you are facing, and the current situation in the game (at the opener, after the opener in follow up goes, what cooldowns do you currently have both).
For 2, there is not a cookie cutter opener that will work against every single comp, but the general idea is: you want your kill target to not be able to do anything to stop the go before it happens (as you get CC on the healer), so it is a good idea to have them in any form of CC (sap, gouge, dragon’s breath and sheep are the best options for that, when available) while you secure CC on the off target.
I’d say that sapping the healer and using dragon’s breath from invis at the same time on the kill target and then attacking the kill target with stuns before the DB expires is a strong opener in most cases, unless the target can literally do nothing to stop the attempt (i.e no pre sanc, no pre bladestorm, no pre wall, …).