Should I Wet Type 1 Before Compacting?

Yes it will be fine, compact it in 50mm layers wetting it before compacting, it will goes as hard as concrete.

Should I wet gravel before compacting?

Try and wait for the ground to dry if it is a little wet before compacting, but if its unavoidable, add a small amount of large gravel to help bind the wet surface and continue compacting.

Should I wet sub base before compacting?

You'll want to ensure that the water penetrates the entire depth of the sub-base material from top to bottom, but you'll want to avoid flooding the surface. If the base is too wet, you'll find that your plate compactor sinks too deep into surface.