...but this section was the best fit that I could find.

I've got some questions you may be able to answer for me about digital cameras. I'm thinking about going halfsies on a Canon Digital Rebel XTi with my mom. She already bought the camera because there was a good deal at Best Buy that included a longer lens, but she hasn't opened it yet so I still have an opportunity to figure stuff out.

First question... Most of my photos will be astronomical in nature (duh!). This means the camera will be outside for sometimes half an hour or (very rarely) more than that. Being that I live in Minnesota, outdoor photography (especially at night) can get sorta chilly. I'm concerned about the LCD freezing and getting ruined. Can this be an issue? If so, are there any remedies I might try to keep it from freezing in the first place?

Also... I looked at the camera for the first time last night and was able to take some snaps in the store, including a couple with the long lens. It's Canon's 75-300mm EF lens... After I took a picture of a sign about 40 feet away with the lens all the way out, I noticed the size of the sign on the LCD preview screen, when viewed at about arm's length, was about the same size as the sign as it appeared to my unaided eyes. Now I thought the human eye was roughly equivalent to a 50-55mm lens, so the 300mm focal length should have brought it in much closer. I can't help but wonder how accurate the image on the LCD is as it compares to the image size on the final image you get when it opens up in whatever photo manipulation program you use.

Any help would be appreciated!

It's a digital camera - the statement about 50 mm lenses applies to 35 mm film. Essentially a CCD is a lot smaller than 35 mm film so requires different lens characteristics. I think that 70 -80 mm is a better estimate depending on exactly which CCD you are using. Hence the 300 mm telephoto is not as extreme as you thought - think 200 mm max in a 35 mm camera.

Incidentally the Canon Rebel has two features that are not helpful for astrophotography.

1 - Its a CMOS chip, not a CCD at all. In low light a CMOS is not particularly good

2 - Its a 10 Mpixel chip. More pixels = less light sensitivity. You lose signal/gain noise by having too many bins. Look at the dedicated astro CCD cameras - 1280 x 1048 is a huge matrix, most have even fewer.

I have the digital EOS rebel, the 6.3MP version of the xti. I I have never noticed any performance issues in cold weather, but have only had the camera down to about 15F.

I also have the same lens, and I am not sure about what you are describing. My screen displays pretty much the way it shoots. In other words the screen is the picture, but there may be a setting for that ( I don't have the camera in front of me to check)
FWIW I have not noticed a difference between that lens on the digital vs. the 35mm film camera I have, but I have not actually tested that.

When used with a t-adapter on a 130mm reflector I got great moon shots, at least for a very first attempt. With the digital that is.