Welcome to the board!
1. Your breeder should provide you with all the info on what food to feed, quantity, and frequency. Amounts could vary depending on the food, but at this age feeding at least 3 times per day. Their intake will increase pretty rapidly as they grow, you'll likely be adding as much as 1/2 to 1 full cup every 7-10 days. They can put on as much as 2-3 pounds per week up til 6-7 months.
2. Size at 8 weeks has no correlation to size when full grown.
3. Start crate training from day 1. Yes the pup will cry, whine and carry on the first few days while in the crate, and hopefully your breeder has already introduced the crate so it won't be such a big deal. Even if they haven't, it's still not a big deal. Take a couple of old towels with you to pick up the pup, and rub them all over the pup's mom and any siblings that are still there. Put this in the crate with the pup when you get home, it will give the puppy familiar smells and help him settle in.
There is no way I'd put a small puppy in bed with me, for several reasons. Once they are in your bed, you'll never get them out. Second, there is danger that the pup could fall off the bed and injure itself. Third, you could roll over onto the pup and injure it.
You can always set the crate up in your bedroom, which is convenient as you'll be able to hear them when they need to go out. And they will need to go out at least 2-3 per night the first few nights. Once they settle in to a routine, you may still have to get up once a night to let them out as the have little tiny bladders and can't hold it very long. Most dogs will not go where they sleep, so get a kennel with a adjustable inner panel so you can increase the size as the puppy grows.
I won't lie to you, the first couple weeks can be rough. Lab puppies can be pretty horrible with the jumping and biting and chewing, but with a LOT of patience and love, they quickly grown up to be amazing companions.
Raising a Lab puppy is not a destination, it's a journey, you'll have ups and downs, there will be days when you wonder what the hell you got yourself into, and there will be other days you'll just laugh and be amazed at what a great dog you have. Enjoy your journey, there's really nothing better.