I can answer a few of those questions but many depend on you and what effect you are looking for.
I mostly use my flash as fill light so I usually select my camera settings to suit the scene without the flash first. The idea is that I want the camera to see as much of the scene on it's own and the flash just light my subject as much as needed only.
Bouncing the flash etc is simply a preference you need to decide. I think the 430 has a card (they call it a catchlight card I think in the manual) that slips out of the head like my 580 which can be used to deflect the light as well. I often use that too. Angle the head away from the subject a bit and then card bounces it back to the subject giving a more subdued light.
But bounce off walls etc if it gives you the look you need. Only experiementing will tell you what you need to know there.
Haven't got time to go grab my flash and look right now but I think the Zoom readings work only in ETTL mode. As I use Manual alot I don't worry about them too much.
Remember that you ISO makes your sensor more sensitive to light so by using different ISO settings you can effectively increase and decrease the 'strength' of the flash to some degree depending on the scene and ambient light available.
That's about it from me for now ... I'm no expert so others will hopefully have more to say or correct me where I'm not accurate.
Bookmarks