Black Lab Dog House and Feeding

Question
I have a 10 month old black lab and I am attempting to build him a house. What size would you recommend to build.  I had layed out a 3x3x3front and 2ft back.  Went to Menards to buy the lumber and the guy said for a lab that the house would be too small so I left with my head down thinking I was building something big for him and a man had to stomp on me.
Then I have tried to find the correct "puppy chow" for him although he never has a hard stool it is always loose.  It has been this way since I got him and I am not for sure what to expect or when to expect seeing harder stools.  Should I take  him to the vet about this?  Please help me out.
Barking at everyone that passes the house.  What can I do to stop or slow down all the barking?  I wish I knew more before I got myself into this job of caring for an animal.  I could never give  him up as we love him dearly.  The kids love playing with him and walking him especially.  I just need  help with somethings is all.  

Your help needed in nebraska please.  Stacey

Answer
Hello and thank you for your questions Stacey,

The dog house should be around 3 1/2 feet wide, 3 feet deep and 3 to 3 1/2 feet tall, of course a large house would be nicer but this size to me seems large enough for my three dogs combined lol(I don't yet have a dog house built but I see no point my dogs live indoors not out), a lab is only full size at 14 months so he has some height to gain and some filling out to do yet. If you feed nutro, technical,pro plan, nutreance or authority avalible only at petsmart stores the stool will be firm, firmer stools are gained by expensive foods the dog gets more nutrances out of the food it eats so it eats less and poops firm stools, if the dog is eating purina, peggigree/beniaful or grocery store brands teh stools tend to be soft because the dog isnt getting the vitamins and mineral/faats he really needs out of his food and its all coming back out without doing much good so you get a dog that eats more poops more and has runny stools. Barking is becoming something unbearable with my lab I am considering a shock collar at this point she has always barked at people passing by the yard and cats/dogs/magpies and crows passing by the yard but for the past year shes been a big pain with it, I'm so sorry I cant help you about this I only wish there were a simple way to stop the barking but there isnt.