Ok i got two #1 rankings for two certain keywords and I would like to replace the current index file with a new layout. To be more precised a shop. Will that influence my ranking. Would appreciate to hear from others what they think would be best to do? Thanks
You can usually target a few terms and easily hold them with a new site design. It depends how much traffic they bring in + how competitive to see if its worth it. If you follow the usual instructions, content, titles, alts, links etc you should not really have a problem.
if your design is seperate from content or only influences content very marginally - nothing SE are not interested in css or tags they are interested in context and content. If your new design is lighter on html as it uses more css it can help to retain position. Expat