Once you have retweeted, you can visit your tweets to show all your tweets and retweets. At the upper right of the post you retweeted, click the little arrow button and select 'copy share url' and voila. Note that this will give you the link still similar to that of the original tweet, but the last values are different. If you want to get a unique one with your profile name on the link, I will suggest you use mobile twitter application to get the link. (That is what I do anyway). Cheers!
Done the same. The number on the little arrow button is that of the original twit, whether you use desktop or mobile application.
The only way you can have a retweet link is to also post a comment together with the retwitted link but it won't count on the number of retwits of the original poster