Request for help in new refuge set-up

[Lance]

Hi Everyone. Just finished building new sump/fuge for a 90 gal mixed reef, and have a couple questions. The fuge section of the sump holds about 25 gal. I am planning on a 3"-4" sand base and about 20 lbs live rock. First question: How much and what kind of light to maintain a decent macro-algae colony? (15" deep from light to sand base). Second question: What kinds of macro do you recommend? caulerpa?, chaeto?, mixed? What about mangrove, and where do Ifind some? Any advice appreciated.
Lance