The Rotator's items are placed next to each other and the size of each item in relation to the size of the rotator (which is to say, the viewport towards the items list) controls how many items are visible at ones. This is explained in details here: http://www.telerik.com/help/aspnet-ajax/rotator-configuration.html
Thus, it is not possible to only have two items with all possible dimensions of the rotator. If you want to show two items you will net to set proper size to the rotator so that it shows two items only.
On events - you can use the OnClientItemShown and OnClientItemShowing events: http://www.telerik.com/help/aspnet-ajax/rotator-client-events.html
. You can obtain the item that is (just about to be) shown and from that you can know its contents, its index, etc. Alternatively, you can use the OnClientLoad event to find the buttons and attach a custom event handler for them if you need to. They have the rrButton class (all four of them) and then each has its specific class that defines its direction - rrButtonLeft, rrButtonRight, rrButtonUp, rrButtonDown. Using jQuery will let you easily get references to them.
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