If i submit my blog in google !! are all new topics automatically displayed.. or u have to submit each topic page separately
a blog has categories under which you can publish each article. also, some blogs have calanders where you can browse blog entries by desired dates. these archived categoties and calanders can work as sitemaps and G can crawl your individual entries with deep crawl
sitemaps are not always needed. Its just a blog so don'nt worry about it. It takes about 2 weeks max once you have submetted your site to google.