polite wild rat info please?

Question
Hello,
I will try not to write a book to you, but we feel like we are in kind of a different situation.  We moved into a very old farm house about 3 years ago and when ripping out an old bathroom, we discovered there had been a rat (probably a very large rat) living in the house at some point.  We figured it was probably gone due to no people living there for a very long time.  Well we found out about 2 years after we had been living here that the rat either still lives here or came back.  Of course at first we were not too happy to have a rat living in the house with us!  We have chickens and goats and it does not seem to be bothering them, it does like to steal my fresh eggs if I leave them on the counter and anything else for that matter!  He is very much set in his ways as a rat.  He comes up from under the house behind our stove and comes onto the stove and counter and sink area.  He will take any food items available and drink any water or liquids available and go back to his home area.  Of course everyone we know tells us that we are going to get sick and he is going to bite our children or something crazy!  We are very big animal lovers and really did not want to hurt him just remove him.  Well he is very smart and avoided anything we tried.  We set it so that we could see him taking some food, he is not scared to come out and look to see what we are doing.  Even with 4 small busy children in the kitchen, he will poke his head out and look at us then quickly retreat behind the stove.  We have come to enjoy him now.  We may have another smaller one also.  He (they) have been consistently living with us for about a year to a year and a half.  We now tell people that he is a very polite rat.  He does not urinate or leave droppings on the counter or stove.  And very rarely does he knock things over.  We have to be carefull not to leave things that we will want to eat the next morning on the counter.  (And we don't put our eggs on this counter any more!)  Anyway, we have become somewhat fond of our rat.  We would like for him and his friend to be able to live here and not have any problems.  One more interesting thing, we many large indoor cats that are great hunters and have rid us of all mice.  They do look for and at the rat, but I think they know he would be quite the match for them.  And he does not come down from the counter and stove area.  My point of writing you is you seem very knowledgable on rats, maybe you could answer some questions for us and help with our concerns?  
1.  Will he bring more rats?  Are there probably more here than we know of?  Is there a way to find out if there are more?
2.  I now leave him (them) food and water on the counter.  Will that keep them in that general area and keep him from going out and looking for food (like in my chicken coop)?
3.  Will he eventually become our "friend"?  (Not our pet)  We do try to stay in the kitchen sometimes to watch him.  He is really neat and very large (his foot print is about the same size as our smallest cat and he is very long and very healthy looking)!
4.  Does he carry all the crazy things that people say he does?  He seems very clean and grooms himself often.  Do they generally carry disease?  
5.  Is there a way to tell how old he could be and how old he could live to be?
6.  Is there a way to tell what kind of rat we have?  
7.  Should we be doing this at all?
If location information would help with any of this, we are in the southwest corner of Indiana and live pretty rural.
Thank you for any help and information!  Our children are very fasinated with him also.  We are homeschollers and would like to use this as an opportunity to let the children learn something outside of what "most" people think about wild rats.  Thanks again!
Blessings,
Amy  

Answer
Hello Amy,

1. Yes, your rat will bring more rat into your house, as just 1 pair of rats can produce about 120 more rats each year.

2. Even if you feed the rat, he will go all over the house looking for food.

3. No wild rat will be come your friend. If cornered he will bite.

4. Pet rat are clean but can still carry disease. Wild ones will carry more disease.

5. Wild rats only live for 18 months - 2 years. Are you sure if a Rat? or the same rat?

I'm sorry but I can't help you with questions 6 and 7. As I'm in the UK so don't know what type of rats you have there.

I hope this has helped.

Take Care
Jess
Nitros Fancy Rats