In SweetRice ,page includes category page,post page and automatic page like sitemap etc,
we may create new page at Dashboard -> Post -> Create menu.
In every post page or category page,SweetRice show the whole content of post,if you want just show part of post and show readmore link,you may do it yourself if necessary.
Yes,normally 10 posts per page (category page),we can update the variable? in inc/do_category.php $page_limit = 10;? (at about 23 rows) , change the number 10 to your number and update the file to your server.
Yes you can,the online store plugin maybe? released at aug 2011,if you have any idea please let me know.
SweetRice is a very simple program,we can easy to modify it,and if any feature important for all people ,we will create a plugin or include it in next version.