First- Keywords. Is it necessary to place them in the meta tags of a document if they are already in the content of a document.
Second- I have a couple of images acting as links on my index.htm. One is to the HTML Kit website and the other is for The GIMP. I've been told these can hurt my SEO efforts. Is this true?
Its a good idea to add MegaTags to your website.
And, I've never heard of people having any troubles with that.
Only, if you change your domain, sometimes your site gets "deleted" of the search engine for 1 month.
Meta tags help but only to an extent. These days most SE dont even look upon the meta tags, as many evil SEO sites filleec them with useless keywords. And the SE look on the number of outgoing links, if there are too many they may suspect you as spam. As long as num of links is reasonable, dont worry.
Google doesn't about Meta tags.
As for images, you shouldn't use them as internal links, you should only ever use text. As for header images, place your keywords as the alt text (but dont go overboard).