As far as reducing the amount of times you feed, just go ahead and do it, he might hate it at first but he will get used to it and quite fast.
For your second question, yes you may leave your fur ball at home and crated all day, provided he is very well exercised in the morning and evening. Dogs like the Labrador Retriever need a whole lot of exercise and mental stimulation or they can become very disruptive and destructive from boredom and a lack of physical activity, so if you want your pooch to be happy and healthy, not destroy your home or howl all day in his crate while you go to work, you have to exhaust him. For a lab, good exercise is brisk walk of at least an hour, an hour and a half long or an hour at the dog park if your dog plays and runs around, you can use backpacks (my favorites http://www.ruffwear.com/Products/dog_...) and such to tire him out faster, use toys like flirt poles and such, all kinds of possible ways to tire him out but they must get him exhausted. Then you can leave him to sleep it off. But when he's been a good boy and has stayed in his crate for 8+ hours, he will need the same exhaustion again and you will get a nice evening of relaxation and sleep for the both of you. You can also add brain games and short fun obedience training sessions since tiring the ind will also tire the body.
If you don't see yourself having the time or energy to give him this much activity, I recommend you hire a good dog walker or find a doggy daycare to help you with this, you and your both will only be happier for it. Rover is full of great folks who really love their work and adore dogs so look up the ones in your area with great reviews, lots of repeat business, go to more than one meet and greet if you want and see who you prefer. Plus with Rover, you get daily reports with the walks mapped out on GPS and tons of photos and videos so you know exactly how long and how far the walks were and what your dog wa sup to during the walks or dog park outings.