Any tips how to get a 8 year old to stop being so nosy and obnoxious?

Of COURSE they are a "package deal".  Would you seriously date a guy who would abandon his child for the likes of you? Laughable!

You need to find another boyfriend. If you do not have the patience to handle an8 year old second grades, then you will NEVER be mature enough to handle an adolescent or teenager.

Let the guy go se he can find someone more compatible with his lifestyle.

It is Okay not to want to be bothered with a spouses child. It is Okay that you recognise your dislike of having his child present .

You are free to go.

You are not ready to be a parent. Leave this man and his child and do everyone a favor. You are expecting a child to act like an adult, that proves you are not mature enough to handle this type of relationship.

Obviously you don't know much about children.  Kids love to talk if there's an audience, and this girl seems to like you.  Take that as a great compliment.  Those are perfectly normal behaviors for an 8 year old.  What you need to do is engage her in doing things with you.  Let her help you with the laundry by teaching her (if she doesn't already know) how to fold things neatly and put them away.  Let her help you in the kitchen when you're preparing a meal.  Her mother isn't around to do those things, and she needs a female adult to teach her.  She also needs someone to talk to, and the fact that she loves talking to you is again a great compliment to you.  When you're really tired or don't feel like talking, have something for her to do.  Get some books and tell her to read one, and when she's completely through with the book, she can tell you what is in it.  That will keep her occupied for a while.  If you are talented in arts or crafts, teach her how to do things on her own.  Get her some supplies and let her create some pictures or some Christmas decorations.  Then put them up where everyone can see them, and compliment her on her talent.  Your boyfriend will love you for being kind to his child, and she will forever be grateful.

I hate to break it to you, but she sounds like a pretty normal 8 year old.

give him a laptop to play minecraft on, that will distract him 

Kids are naturally active, noisy, and curious. That's part of being a kid.  If you don't want that in your life, they you need to find a guy who doesn't have a child.

It isn't clear whether the child is just a normal kid or if the father has failed to raise the child to be respectful of adults. The child may also see you as a threat or competition for her father's attention.

It is not your place to correct or discipline your boyfriends daughter.  You can talk to him about your concerns see if he is willing to work with his daughter to learn to be respectful of your conversations and or play quietly by herself for short periods.  Those are normal expectations of an 8-year-old.  

You, as the adult, also have a responsibility to include the child in some things if you are going to hang out in her home and date her father.  Again, if this is not your cup of tea, then end the relationship and look for a guy who doesn't have  kids. 

Children have to be taught how to behave.  Set boundaries and if she crosses the boundaries take a belt to her backside.  

She'll learn manners, one way or another. 

She is her father's child.  Not yours.  You should have second thoughts about staying in a relationship with this man, because his child is always going to come first.  Children are naturally inquisitive, may she's just a smart child who wants to learn as much as possible.  Could be a future POTUS.

Look at it from her side, she has lost the connection with both parents, now you are in the picture and you are going to take her dad's attention away from her. He has told you his priority, his daughter comes first, you have to put her first also, or he won't see you in the picture. If you want a relationship with him, make one with her.