The Behlens does dry fast and can be blotchy. My solution is to apply the stain, then wipe the whole thing down with denatured alcohol after the stain application to even it out.

I have use the retarder once and didn't notice any epoxy issues. Since then I've just done the denatured alcohol wipe-down thing.

If you want a lighter color, you could dilute the stain with alcohol. Maybe mostly alcohol with a little bit of stain in it.