Overactive Imagination Or A Paranormal Experience?

I would say this is more of a few experiences I've had and things that are still happening than a 'ghost story' as some would put it.

The first thing I think is worth noting is when I was younger, I would talk to people I thought were there but who nobody else could see or hear. I think my mum humoured me and thought 'Oh, it's just an imaginary friend thing, she'll grow out of it' which is understandable; kids do that kind of thing all the time, but I could actually have a conversation with these people; I would speak to them and they would speak back, I could hear them clearly. Most of them were children around my age but not necessarily from the same time period I was born in; for example I once saw a little girl who was dressed in clothes from maybe the 40s or 50s thinking about it now. Maybe I did just have an overactive imagination and I expect most people will think that, but because I never saw the same person twice and most of them wore clothes from different eras I'm beginning to wonder if it was something more than just a few imaginary friends.

This happened until I was about six I suppose, and I remember that winter (1999) I went out for a drive with my parents. We were driving through some countryside, I can't remember exactly where it was now but I remember there were woods on either side of the road we were driving on. I was looking out of the window through the trees and when I saw a blonde girl who must have been around twelve or thirteen, she was quite pale but not the way people look when they're sick, had bright blue eyes and her hair was stuck together in sections like your hair does when it gets wet, as if she'd been out in the rain. She was wearing jeans, a pair of dirty white trainers and a white coat with a red jumper showing a bit lower than where her coat stopped. I wouldn't have thought this was unusual had she not been on her own, completely still even in the wind and the location wasn't so weird for someone to be walking; there were no houses for absolutely miles and we hadn't even seen another car for about forty minutes, let alone houses where she could have lived. After I saw her (she was looking right back at me by the way; she looked a little bit scary somehow but not abnormal) I've only really had this kind of experience.

Since her I've only been able to see or speak to people I've seen or heard; I can't merge the two, I either see them or hear them. I see people more than I hear them but it's usually when I try to talk to them that they go. I have no idea why; I don't mean them any harm, I just want to know why they're here really. The other thing I get is that sometimes I randomly feel presences of people but don't hear or see them; this is usually only upstairs or in my kitchen but none of these are really worth noting down, specifically.

This is an experience of my dad's: Just before I was born he was house-hunting with my mum, and when they were looking around our old house they went down into the basement. I know it's probably going to sound stupid now that I've said it was the basement because it's usually known as the creepy part of a house but my dad is a total cynic on stuff like this, anyway he swears he heard a man's voice tell him to 'Get out' of the basement. He said just after he moved into the house we live in now, he kept having a really strange dream that he was washing up and as he was leaving the stuff to drain he looked up at the window and kept seeing an old man's face looking in the window at him.

I was just wondering, can anyone explain what might be going on here? I think some of these are a bit more than coincidence and was wondering if anyone knew anymore than I do. If you do please tell me what you think; I'd be really grateful.