Labrador retriever questions

Question
Hi,
I have two Labrador Retriever females (one black and one yellow), both are sisters aged 9 months. I have a couple of questions that I would like to have answered:

1 - Is it possible for Labrador retrievers to acquire guard dog/attack/manstopper training or would that be counterproductive keeping in view its benign personality?

2 - I always walk my labs with a leash on: Whenever they see a dog from far away they act all confident and protective however up close and personal, they start getting a bit freaked out (be the other dog a rott or a cocker Spaniel). Is this normal and will my labs grow out of this as they grow older? (remember they are just 9 months old).

3 - Consider a scenario when the master (in this case, me) gets involved in a pyhsical tussle with a stranger. What kind of behaviour can I expect from my Labs? Will they attack the stranger? If yes then with how much ferocity? Equal to that of a German Shepherd?

I would really appreciate help with regards to my questions.

Answer
Hello, You can likely get labs guard trained but to me it would defet the perpose of having such even tempered dogs...labs have little to no guard instinct. My 3 year old spayed black lab "Haylie" will act protective and jump and bark at the back gate and grumble/growl but would never dream of persuing an intruder.... during walks she will pull AWAY from barkiung dogs because she is frightened and will cower slightly when a stragers pets her while walking by...yet I've had her since she was 3 mnoths old and have other dogs and walk her every day and she sees lots of people.... for insctance today my brother in law is fixing something on his truck in the yard with his friend and I sent my dogs out to potty the jack russell terrier and boston terrier whnt out without heistation but I had to push my lab out lol...she was also in the corner of the yard stairing at tehm when I went to get them and as soon as she saw me she came in! shes a big coward honestly...I think male labns must have more courage!.  I have always wondered  If I were attacked thou most rapeists/thiefs wouldnt dare apporch someone walking large dogs) what my lab would do ashe is protective of the yard but would she attack? I really dont know and therefore cant help with this puticular question.  A german shepard makes an ideal gaurd dog and would react with much more frocity then a happy go lucky lab.