How can I strip all html formatting from text when pasting into KendoUI Editor?

For pasting the only the text you might define a paste handler that remove all but text. This is as simple as:

$("#editor").kendoEditor({
    paste: function (ev) {
        ev.html = $(ev.html).text();
    }
});

The paste handler receives as argument an event that has in html the text being parsed. We can use jQuery for getting only the text using $(ev.html).text()

For removing the shortcuts, and as far as I could test it with latest Kendo UI version, if you define only the tools that you want, only those shortcut are active. So if you say something like:

$("#editor").kendoEditor({
    tools: [
        "italic"
    ],
    paste: function (ev) {
        ev.html = $(ev.html).text();
    }
});

Only italic shortcut <ctrl>+i is available. If you leave tools array empty then you do not have any.