Refugium help - need info and ideas

[Twinn]

I'm building a 40 gal tank and thinking of adding a refugium to produce pods for a mandarin but, I got a bunch of questions.

What do I put in the refugium sand or no sand, live rock, cheato?

If I use a filter sock will it catch all the pods making the refugium pointless?

Should I just run Np pellets to up my pod production?