If the RadToolTip is in an INaming container (such as a master page or an update panel) its ID will be changed by the framework and this is a very likely reason why you cannot access it. In order to get the correct ID you would need to obtain if from the server,for example:
tooltip = $find(
As for jQuery - our controls internally use jQuery for some of the functionality and therefore output it to the page if needed. This will not impact your own jQuery if you are using it, neither it is required that you add your own.
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