Straight to your questions:
1) We have not implemented the RadToolTipManager as the RadAjaxManager and the ScriptManager due to the following reasons:
- we can have more than one manager on the same page - e.g using with different zones
- it is absolutely valid scenario to want many different tooltips with different settings on the same page as well as on different content pages with the same Masterpage.
2) The RadToolTipManager is as all other controls and thus it is not added to the Items collection by default. You can test with standard RadControls as well and you will see that they are not added there because this is not needed in the general scenario. However, you can implement your own collection or use other general ASP.NET to pass the needed information.
3) The general manner is to use FindControl but ASP.NET provides other mechanisms to achieve what you want - e.g you can store the manager object in the Session object, etc. Note, that this is a general Master-Content scenario and you can implement what you need for example with a standard button - once you reference it in the desired manner just use the very same logic for the RadToolTipManager.
On a side note, you can also simply add additional RadTooltipManagers in your content page where needed - this will not affect the performance significantly.
I hope that my reply is detailed enough and helpful, let me know how it goes.
the Telerik team
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