Those issues are caused by Twitter's default share code.
If you copy the code directly from twitter and paste it directly into your SHOWTHREAD template (basically what this mod does) you will have the same issues.
I did notice Twitter added a new IFRAME option for the Tweet button. It seems to fix the count issue but the URL still doesn't shorten until after you send the Tweet.
I have not updated this mod to use the twitter IFRAME code. I'm not sure if/when I will. I have released
instructions for those with the Gold version of the mod to take advantage of the IFRAME option since the Gold version has an option to easily add new buttons.