01. Neutering/spaying your dog
If you don't plan to breed your dog, you should absolutely get him or her fixed.
Neutering a male Brittany
Despite what you may have heard, male dogs will hunt every bit as hard and will develop the same muscle tone as an intact dog. On the plus side, he'll hump less, mark less and generally be less of a pain in the butt.
There's nothing wrong with neutering anytime after six months but, if you wait until he's 18 months or so, he'll look more like a mature male dog. It's only an appearance thing, though, his personality will end up the same no matter when you have it done.
Neutered Brittanys do tend to get a more "wooly" coat and are prone to overeating. The coat will require that you thin it down every few months so it doesn't get full of briars. A Mars Coat King #20 http://www.petedge.com/product/Mars-Coat-King-Strippers/44334.uts works wonders. As for the overeating, you should already be feeding him one or two scheduled meals a day and taking away anything he doesn't eat. You'll need to adjust his intake to keep him lean once he's fixed. If non-Brittany people describe your dog as "too thin" he's probably about right. You should be able to see a rib or two when he's standing still. If you can see three, up his intake a bit. Never cut back on his exercise.
Spaying a female Brittany
There are many benefits to spaying a female Brittany and no drawbacks. Once spayed, you no longer need to worry about her coming in season during hunting season and there are certain cancers and infections that become a non-issue. You may see some of the coat and eating issues described above.