I don't really have an opinion on whether or not he was expecting her, however maybe she offered to park down the street under the guise that his room mates wouldn't know she was there for sex. It seems like her and TA kept a lot of their encounters on the down low.
Yes, that's a possibility as well. Assuming she was an invited guest, they could have made a previous arrangement for her to not park by the house. Because her cell phone was turned off, it's more difficult to track her intentions as it seems odd that she wouldn't call as she was getting close. Heck, nowadays - people are incessantly on their cell phones; e.g., "I'm 5 blocks away - okay, I'm 2 blocks away - okay, now I'm at the end of the street - I'm walking and I'm calling you from the driveway - okay, now I'm on your porch - oh, there you are - I'm talking to you as I see you opening the door, and so on."
The problem I see with her statement is that she lied about parking in the driveway. If she was an invited guest, not only would the truth have been the easiest thing to say, but it also would have been more helpful to her story of Travis not wanting to be seen with her in public if she had said there was a prearrangement for her to park down the road.
So, either way (invited or not invited), this is extremely important in my opinion. It is a key element to premeditation because she lied about it. If she was invited, why didn't she just say she did not park in the driveway because of a prearranged plan, or that she decided on her own to park down the street to avoid being seen by his roommates, or there was no room in the driveway, or that she didn't want to block his roommates' cars. Anything but lying shows there was at least a reason for doing what she did other than premeditation of a murder.