Sure it is, why not? I think you should put these adsense in less visible place, they're scaring the visitors...
You will have limited control over on page factors because you do not have direct access to some parts of the code. However off site link building is still possible and has no hinderances. I would suggest you don't spend too much time and effort on a blogspot page though because it's hosted for free by Google which means you are subject to their terms, it means that at any point they could decide to remove your blog from the web for no reason.
Yes sure, but my dear friends this is free blog site. The best way u book one domain name which is related to your product and then start SEO & SEM.... ______________ Apply for Loan | Jobs in India | Find Your dream Job Here
Blogspot is great free way to learn, but don't stay long step up to your own domain and hosting package soon!
I would open a word press blog because search engines seem to love SE-<3-WP. every site needs SEO though you could have a great site but with no search engine traffic no one will know about your site.