Are labs easy to keep...or do they shed alot?? Should i get a golden retriever and lab mix?

See i have a lot of space, price doesnt matter, and he will stay in the house. I want a gaurd dog that can tell the difference between an intruder and a visiter. What do u guys think? Will a lab be goood? ill brush him and give him exersice and train him. He will stay home from 10-3 and ill be meeting him in my lunch hour. What do u guys think? And does anyone noe a good trainer and a good place where i could get a lab golden retriever mix?