How do I initialize Ultrabeat? - i want to build my own kit from a sam...

Yes, load the "Drag and Drop Samples" kit - that's exactly what it's intended for.

And yes, UB can load EXS instruments, but there are some limitations on mapping as the UB engine is not intended for playing some more involved instruments.

When opening a new instance of UB it is set to "default" but already contains instruments mapped out on the keys. So if you want a totally empty Instrument you would have to edit that and save it in your template or User Library. If you right click/control+click on any Instrument in the UB mapping editor a menue opens - at the bottom choose "Init" and select the mode you want to be that Instrument in (e.g. Sample/Sine and so on).
You can't drag and drop samples into UB you have to use the "Import" menue - so right click on an Instrument->Init->at the upper left you see the blue import button->menue opens->choose a sample from a folder. Or use the "load sample" function in the sample window of each Instruments, at the upper left of the sample window there is tiny downwards arrow which will unfold the "load sample" menue.

You can't drag and drop samples into UB you have to use the "Import" menue

What version of Logic have you got? 😉

Sure you can... Just drag them from a finder window onto the sample waveform area.

It's kinda of the reason Apple made the preset and called it "Drag and Drop Samples".. 🙂

UUUUUUUPPPPPPS - well I never use UB so I was trying to give a smart answer which turned out to be a desaster 😉 - maybe I should resign from this Forum.....

Notice how I never attempt to answer score questions...? 😉

😉