I was thinking if I got my weezing and used destiny bond then explosion, would it knock out the oppenents pokemon if explosion didn't knock it out? Also if I used explosion and had a focus sash attached to the pokemon would it avoid getting knocked out?
You seem to be missing the important fact regarding this:
The turn you use Destiny Bond is the only turn Destiny Bond will take place. If the opponent doesn't make you faint the turn you use Destiny Bond, then you have to use Destiny Bond again in order to get another chance at it.
This means that using Destiny Bond, then trying to use a suicide attack next turn will not work.