I'll try my best to reply to these. Im very much an amateur but I think in this case thats a good thing.
1) Please correct me if im wrong here but, it sounds like your "style" is point and shoot. You like to carry a camera everywhere you go and take loads of pics. And you dont do it for any other reason than to have the memories. Again, if Im wrong please correct me. I would go p&s camera for this
2) Imo the biggest advantage in going dslr is large prints. I went dslr because my p&s just couldnt produce a good print above 11x13. That was with a Canon S3 is. I dont know how the newer p&s cameras perform with larger prints so hopefully someone with some experience with large prints and newer p&s came chime in. But imo, if your not planing on large prints, go p&s
3) dslr vs p&s. This is a tuff one and it really depends on where you are going to be using your camera and what you need the camera to do. High-end p&s camera have come a long way. They have raw mode, full manual mode, can use filters with the use of adapters and Im sure much more but it's late and I cant think right now. But to answer your question, going p&s you lose the ability to change lens and a big sensor. Those are the 2 biggest advantages a dslr has. Im sure there are more but like I said it's late
4) At that price range you can get a used/refurb/new dslr with a kit lens (maybe 2 if you find an amazing deal). Or you can get a high-end p&s. At this price range and that fact that you dont plan on large prints, I would go p&s.
5) For hiking (backpacking, if thats what you meant?), I wouldnt like to pack a dslr. It's just to much weight and too bulky. The best camera is one you like to take and will take everywhere. I can say this from experience, I leave my dslr at home more times than not. Even for day hikes I dont like to bring my dslr. It's a pain to lug around and it's a pain to take it out of the bag every time I want to photography something. Now I could leave it around my neck but I'll say this, it gets very uncomfortable real fast.
Hopefully some of what I typed made a little sense. And I dont want you or anyone else to think Im anti dslr, Im not and I love my dslr when I use it but I dont use it very often. A dslr can make people uncomfortable when in the city and it is heavy to pack around on hikes. The only reason I have a dslr is so I can make large prints. Here is 2 shots, one taken with a p&s and one with an dslr: Please keep in mind that Im very amateur and I know others could do much better. Both are of the same falls but different angles and lighting.
http://www.flickr.com/photos/kevin_cantrall/1040082379/in/photostream (yes I know, over overexposed)
http://www.flickr.com/photos/kevin_cantrall/3684331401/in/photostream (yes I know, it's not strait)
For this type of photography a p&s works very well compared to a dslr. And imo a p&s will work very well with all kinds of photography except low-light photography and continuous shooting speeds compared to a dslr. Imo from the info you posted about the photography you do, a p&s might be the way to go. I know if I didnt need to print large I would be using a p&s and I would have more pictures (or memories if you will) do to not having to lug around a dslr body and lens.
Sorry for the long post that probably doesnt make any sense, lol