Yes. Quality Backlinks and by the way the PR (internal PR) is always updated FYI. The PR you are saying on the green toolbar is not updating yet... Just wait for its updates.
You need to build your back link and make sure don't give link to other site from your home page. and update your site regularly you will get PR soon can you tell us how old you domain is?
one of my site is having PR1 but have good traffic around 1.5k.PR is not needed for Search Engine ranking
Yes you should remove links of other sites it can also one of the reason anyway I want to ask one thing why you need PR?? PR will not gives you traffic, PR will not gain your ranking on SERPS so why you so worried about your PR? I think the best way is just concentrate on your site promotion PR will come automatically and one more thing go to google.com and search your targeted keyword and open top 10 sites and tell me how many PR they have? then go to 2nd or 3rd page and compare the PR on that sites you will find so many high PR sites still not come on top 10 and some site have PR 1 or 2 and they are in top 10.
Other related links in the content of your page aren't a problem, but if you have sold footer links to unrelated sites you might never get toolbar PR showing because sites doing this are often penalised.
depends from where do you get that traffic, sites about sex usualy get high PR with very hard work visit this blog there is a tutorial and some useful tips on directories directorieslist.blogspot.com