1) Dial Highlighted does not work, and was never intended to work, within Outlook...
From
http://www.unifiedcommunicatorexpress.com/Faq.php page:
How can I dial from Outlook?
Instead of dialing through Outlook, what IOC (and UCExpress) actually does is allow you to search your Outlook contacts and select the number you wish to dial.
To enable the searching of your Outlook contacts, left click on the search button (the one that looks like the heads) and select "Search Outlook Contacts" from the menu - the little Outlook "head" should turn on.
You can now type in the first, last and/or company of the contact you're searching for. A menu of matches will appear from which you can select your contact's number to dial.2a) Not from Outlook, Mitel's UCA, Broadsoft's Enterprise Assistant, and ESI's VIP doesn't do this either (all search Outlook contacts).
2b) Not that I am aware of, Mitel just uses UC Express as a teaser for UCA, although for some customers it is sufficient in itself so Mitel has little incentive to update it as long as it works reasonably well with current software.
2c) I am not familiar with Skype