Hi Jakub. Did you make any progress on the first point (ie. plain JSPs inside Seam/JSF)? I'm about to embark on a similar project.
Obviously you can change the web.xml mapping for the seam filter to just include the new JSF pages, but I was hoping to keep the filter at "*", to save re-organising our existing JSF pages.
Anyway, once you change the seam filter to not include your JSPs, plain HREFs seem to work ok. But I'm not sure how to make controller actions, redirected through pages.xml, work - they still have the .seam. Any advice appreciated ...