1. make sure that the nagative is flat when u scan it. on the table scanners there is not press to make it flat, and i guees u know what it means.
i have the same problem even with the negative scanner. the negative carrier of the scanner is damaged and it cannot keep the negative flat. but i dont mind, cause i use the scans only as proofs. exemination is done only on the light table with x15 magnifier.
2. tiff - is the best as far as i know. but note... when u scan u have to make the software of the scanner correct for u. test it. there are lots of functions in the scanner software. "curves, contrast, brightness etc etc"
3. get a newer photoshop, if u really need to work on the files. no matter how good is your scanner or your negative, u have to give it appearance u want.
4. for web - only afater finishing to work on the photos give it the function of "save for web". in that window, first insure the size of the image, and then if the size of file is too big, reduce the quality.

well that is from one who himself asks basic questions about digital