Dominant Golden Retriever. Help Me please!?

I have a 15 month old male GR. He has NOT been neutered yet, but that is in the works. Over the last several months i have noticed his behavior changing and it seems to be getting worse. He growls and shows his teeth when it comes to his food/chews, certain toys and his bed. however things dropped off the deep end this weekend. He actually bit me. also last night it seemed he was blocking me from walking into the dinning room. I have done some research and realized that my initial characterization of his behavior as aggressive was incorrect. Hes dominate, fighting for rank over ME. This is my first dog. He hasn't had any formal training yet, but understands some simple commands such as Sit, heel, down, no, back, drop it and give. After reading what seems like 100 different articles on line today, the info doesn't really seem too......difficult. They all say about the same eat before he does, not allow him through doorways first, do not allow him to put his paws on me, not to sleep in my bed, etc. all of these things i do already except eat before him. Obedience class is a good way but if i could have afforded that i would have already done it. I need to do it now i see, so i will save some money and get him in a good one, as soon as i can. My question i guess is this. 1) Are all these articles true? Is really not that involved. Just consistent calm assertive leader? Or are they just simplifying a difficult situation. 2) Do we need Professional help 3) Could having him neutered and obedience class be the Solution? Please help! I know i have a lot of work ahead, and im ok with that. I love my dog just as much as you yours. I just cant live in fear of my dog in MY own house! How long could it take to see some improvements? Thanks soooo very MUCH!