Performance and usability are great. The fact that it integrated into tabber without any problem testifies to the quality of the plug-in.
The plug-in is very powerful but easy to use, in part, because of the excellent documentation (including code snippets). Support was excellent. I requested a change to the plug-in at about 10pm. I had an updated plug-in in my inbox at 7am.
The Paypal or Google Checkout address is asked just to confirm the previous purchase and assign you a priority support, you WON'T be billed. In fact there isn't possible to bill a Paypal or Google checkout account without providing a password and we NEVER request a password.
If you prefer you can submit your request support directly to the email info[at]joomlacalendars.com (replace the [at] by the @) or post a support request at http://www.hotdreamweaver.com/support/ ... in any case you will get an answer and solution from our support team.
According to your description the problem is a conflict with some of the CSS styles that you are already using in your template, please contact our support service and you will get a solution in a timely manner.
Please let us know any other comments. Thank you.