make sure that you do something like doing offpage optimazation stuffs. and wait for the pr updates.google pr updates quarterly.
also remember that google are about 3 months behind with the data they use in the toolbar updates so you may have to wait till the pr update after the next one to get your site updated.
Get some links and wait till next PR update... Here are a nice resource for PR updates: http://www.seocompany.ca/pagerank/page-rank-update-list.html
Keep Link Building for your site. Your site will have PR when Google will update the same. Usually G updates the PR by every 3 to 4 months. Last PR udate was in Sep.
Only 1.5 month? I wait for almost half year to get a pr1 for my website. Only wait is not enough, you shall adopt some SEO actions.
Yes,it's possible if it has decent links.. Hey,get a link on my pr4 site for $5 only and it will help your site(see my signature)
Apart from backlinks I would suggest you to populate the directory. Once the dir has enough resources and relevance every thing rest would be just details. PR is only a matter of time focus on building the dir. Jus a suggestion .
Just stick with getting some good quality backlinks, and have some patience and everything should eventually fold into place.