It is better to write your own content or hire somone to write it for you. Content is very important, especially if its unique as in different. When updating content I found its best to update portions of it. Leave the important content intact such as the beginning of your page. Content for each page should be unique to a certain degree from other pages.
Everytime you make a change to your site it is considered an update. I would suggest a slow and steady approach for updating. Taking small steps is better than giant leaps. Give the SE time to digest the information.
Contrary to most webmasters I would shy away from rss feeds for security reasons mostly.
Updating daily in small amounts I found has no ill affects. A big topic to be discussed. greek39