Do you need to format your memory card every time you "empty" it (burn a cd)? I've never formatted one before, unless of course my old PowerShot did it automatically when I deleted all of the pictures.
According to what I've read, formatting your card in the camera will generally speed up the saving-to-card functions. You probably should format the card once in a while; after dumping the pics to your hard-drive would be a good time ... but you don't "have" to do it.
There have been some reports, on other sites, of S3's corrupting an SD card. However, nothing has definitively pointed at the camera over a poorly made SD card.
I'd play it better safe than sorry ... transfer pics as soon as you have the time and reformat the card before taking a new batch of important pics.
Now, I'm trying to figure out the "recording pixels" and "compression". From what was said earlier by LPZ Stitch, I think I should have the compression on SuperFine, right? That would be a better quality photo, but less photos on the card? I have two, 2GB cards now so I think I'll be fine storage wise. I really don't understand the pixels though. From what you said, Large would be a good choice? Does this also mean better quality?
Recording pixels relates to the overall size of the pic (p37 in the manual):
L = 2816 x 2112
M1 = 2272 x 1704
M2 = 1600 x 1200
S = 640 x 480
W = widescreen = 2816x1584
Large is good for printing up to 11.7"x16.5" prints. M1 is good for up to 8.3"x11.7" prints. M2 is good for 6"x4". S is good for sharing through e-mail or otherwise online.
M1 is a good size for vacation pics ... I've never made 11x16 print from any vacation pic!
Compression is a JPG thing ... it's usually called "quality" in graphics programs (like Photoshop). The higher the compression, the smaller the file will be but the less detail it will preserve (especially when zooming into the picture).
Compression works by combining colors that are "close" into bigger blocks. This is often called "lossy" meaning that some detail gets lost.
In terms of image quality:
Normal is the "worst" ... higher compression, small files, but less detail.
Fine is middle of the road....
Superfine is the best ... lowest compression, large files, lots of detail.
There is supposed to be a way to get RAW images (meaning no compression at all and split into three channels R/G/B) out of an S3, but I've not found out how to do it. RAW image processing is more "professional," and you need to have good programs (Photoshop, etc) to take advantage of this.
Also, I have the panasonic alkaline batteries in the S3 at the moment--the ones it came with. Is it okay to switch back and forth to the rechargables once I buy them, or should I stick with one or the other?
You can switch back and forth without worry ... it's one of the best reasons to get a camera that uses AA's instead of proprietary rechargable batteries.
Not only are AA's (even a set of 4) cheaper, but if you ever find yourself with dead batteries (say after a long day at Disney!) you can just buy some standard AA's from any shop and be back in business. With a proprietary rechargeable battery, you'd be out of luck. Any kind of AA you can buy at a store will work.
Just don't mix battery types; always alkalines with alkalines, and Ni-NH with Ni-MH....