I have lots of old slides and should probably digitize them? What is the best way of achieving this? What kind of touchups might be necessary?
If you would like to scan the slides the "Epson Perfection V500 Photo Scanner" seems to get good reviews for slide scanning as well for scanning 35 mm negatives - see amazon (4 stars and 281 customer reviews): http://www.amazon.com/dp/B000VG4AY0/
If you would like to outsource it - ScanCafe might be a good option: http://www.scancafe.com/
You could get a film scanner ... although you would probably want to get a good quality product, as the lower end models do a very poor job.
Another option would be to find the slides and/or negatives you want scanned and send them to a photolab that can do the scanning. If it's a good lab (I've used Helix Color Labs in Chicago) they can get you very high quality scans with high resolutions.
As for touching them up ... I have to defer to people more skilled in image editing. I suspect, however, that most consumer photo editing programs have built in recipes to do a fairly good job.
I bought an Epson V700 Photo a year ago to try and digitise some of my old negs and slides and have been very happy with the results. It will scan 12 mounted or 24 unmounted 35mm slides at a time as well as scanning larger format film (up to 10 x 8").
I tend to scan to TIFF at 3200 dpi and then retouch in Photoshop before batch converting to JPEG to save space. The retouching is dust/scratch/watermark removal (mainly with spot healing, patch and clone tools) which can be pretty time consuming. I sometimes also need to remove colour casts but try to eliminate this at the scanning stage.
It's worth deciding what you want the scans for before you go to town on the retouching. I found it was only really practical for me to retouch photos I wanted to do something with immediately (print, email or upload to a gallery). If I've put the work in I also keep the TIFF along with the JPEG so I can go back to it later if necessary.
Having the folders full of (unretouched) JPEGs is great though and so much better than having to look through contact sheets or a loupe. I've rediscovered several images that I missed at the time I took them as they didn't look like much as 35mm negs.