Twitter's New Link Shortening Service

Twitter sent out an email a few days ago detailing their new link shortening service, using the URL http://t.co/.  Reading through it, I thought it was nice at first, but after finishing reading the email, I have some concerns.

• First off, its use will be automatic and therefore mandatory.  Will this be the case even if you've already used another link shortening service to shorten the link, as I do with bit.ly?
• Second, are they trying to destroy all other link shortening services?  The number one reason there's so many of them is Twitter's retardedly low character limit.
• Third, the only thing I really like is the preview feature, which is something all other link shortening services lack, save for TinyURL, which is ironic because it produces long links in the spectrum of shortened links.  Bit.ly has a Firefox extension that adds previews to other shortened links, but it has security issues.  Since it remotely loads a CSS file from their servers on every site you visit, bit.ly gets a nice list of every single site you visit, whether it has any shortened links or not.  They claim to not store this information, but I don't believe them any more than I believe Facebook when they say beacon data isn't stored for users that turn it off.  Those beacons still get sent, the setting only "controls" whether or not Facebook ignores the data.  It's probably a placebo switch, given the appearance of doing something while in reality not doing anything.
• Fourth, and possibly most important: Twitter stated that link clicks will be logged "to provide better and more relevant content to you over time."  To me, this means data mining for the express purpose of tracking their users' activity for marketing and advertising.  No thanks, I don't want to be tracked or advertised to.
• Last but not least, how exactly will the automatic shortening work?  Will it happen as I paste the link into the tweet, or after I hit the Tweet button?  This pertains mostly to the remaining character count.  Will it be accurate and shorten the link on paste, or will it be inaccurate and force me to stare at a negative number, unsure how long my tweet will actually be with the link shortened?

Link shortening integrated with Twitter would be a very nice thing to have, but it really should be optional.  Furthermore, if they made changes to the way they process and store tweets, the length of a URL wouldn't matter.  URLs have some required formatting, beginning with the protocol designation, and needing spaces to be encoded in order to contain them, so therefore a simple regular expression can find any link and exclude it from the character count.  They could then selectively shorten the link depending on a user preference or for mobile browsers.

Kind of unrelated, but it makes about as much sense so I just have to rant about it: Why do people think it will actually work when they try to retweet a message with their own commentary added?  It doesn't.  It doesn't register as a retweet.  In order for it to do so, the retweeted message must be identical, just with RT @username in front.