I can recommend Atlantida Dive Cebter as well and what an experience for your lads
There are some excellent restaurants in Costa Teguise try La Chimnea in los Cocharas and Las Maretas (you have to book) further up by the post office, if you are on a budget try Coffee and Cream behind the police station they do 2 meals for 12.90 Euro all home cooked food plus John and Zoe make you so welcome.
If they are into surfing then a trip to Famara would be excellent I believe you can have lessons there as well.
If they fancy wind surfing there are places in Costa Teguise that offer lessons it seems to be a big thing on the main beach.
Would also advise jackets for a night time and also in case of a cloudy day it can get chilly in the wind especially if you go upto fire mountain.. which is a must on any trip to Lanzarote.
Hope you have a good holiday
http://www.thecathouselanzarote.com Boarding Cattery
http://www.itsyourpartylanzarote.com Balloon Decorations & Pippin The Clown
http://www.rebooote.com Bouncy Castles & Inflatables for Sale & Rent