The 3/8 combination hone is a good place to start. The Norton 4/8 is also good.

On average, you hone until you're done. If it's one that previously shaved well and just needs a touch up, you would probably be best served to try a few passes (10-20) on the 8K first. If that doesn't help, then do passes on the 3K until it's as sharp as you can get on the 3k. Then you'll do passes on your 8K until all the 3K scratches are gone. Don't get hung up on counting passes, it's the performance of the edge that matters not how many laps you did. What it takes will vary with steel types, pressure exerted, and of course experience.