At 14 your brother is fine to start lifting. The key to lifting for fighting is explosive power as has already been mentioned. Personally, I am big into Olympic style lifting these days and I haven't been this explosive since I was in high school. If you want to try O lifts, go to
www.danjohn.org and download his ebook and watch some videos. There are also good videos on the crossfit site which I think as already been posted.
Also this guy writes a column for MMAweekly which has some great stuff people can to from a home gym.
http://www.workingclassfitness.com/
My personal workout consist of the following exercisesL
Power Snatch (best exercise name ever)
Power Clean and Jerk
One handed rows
Pullups
pushups
Swing snatch performed with a dumbell
Various ab workouts
This one I don't have a name for but I grab a plate and work it in a circle from the front of my body and around my head. The Militech boys all do it and it is a great tap workout.I don't do them all at once, I mix them up and sometime throw in a variation or just a different related exercise to keep it from getting stale.