I have an xr15 pro on my nuvo 20 and I like it. it does leave both ends with less light though so a better option may be 2x ai prime hd's for the cost of that single xr15 pro. I have the aqua gadget spin streams on mine and I like the random flow. They are a little loud until they get a good biofilm on them and require being cleaned every so often to continue spinning so keep that in mind. I have a single mp10 for flow in mine and run it on a program between 10-40% flow. Since I am upgrading, this tank will become a frag tank and I am taking a good look at the current usa eflux loop 660gph wave pump set which comes with 2 powerheads and controller. might be worth taking a look at yourself. The one thing I would most definitely recommend is an ATO. I use the icecap ato on my 20, and the autoaqua smart ato micro on my 10 and I love them both. A lot of people also recommend the tunze osmolator. Lastly, while you may consider a skimmer, I don't feel one would be necessary for this kind of set up. I do use an eshopps nano skimmer but you have to perform regular maintenance on it for optimal operation. Stick with water changes until you decide they aren't keeping up with nutrient control
I like utility fish for my reefs. A six line wrasse for pest control, a tailspot blenny for algae control and a goby/pistol shrimp to turn over the sand bed. Harlequin shrimp are cool critters, however they will quickly starve unless you plan on adding asterina starfish regularly.