Yes; Twitter retweets are generally better than Twitter favorites for driving traffic and helping a Twitter status go viral. If somebody influential retweets your status, you could get hundreds of additional retweets from a single retweet. We've seen some of our customers get hundreds of retweets in a day after using our service.
Yes; Twitter retweets send your status to everybody on a Twitter profile's following, and if they have a large following, that could be thousands of people. Make sure the tweet you want us to help you get retweets to has a link to your website so you can take advantage of Twitter's traffic.
They are both equally valuable. Most of our customers purchase followers to grow their audience, and then after they post an important status, they'll purchase retweets and favorites to increase visibility and traffic to the tweet. The combination is what helps grow a Twitter profile into an authority account.