After installing LR CC and opening the first time it will locate your LR 4 Catalog file, Make a Copy of it and Convert that copy to a LR CC/6 catalog. Giving it its own folder and Previews folder. Leaving your LR 4 catalog in tact. So yes it will automatically include all images that are now in the LR 4 catalog.
As for Preset, No it will not. It might with some but not others. It's been several months since I install LR CC so I don't recall what was carried over and what wasn't. IIRC I had to reinstall the NIK collection and had to manually copy over other things. Luckily I upgraded from LR 5 to CC. You might find some of the add-ons you have, Plugins, won't work with CC. You will need updates for those that don't work.
Yes, once you will install Lightroom CC and launch it, it would upgrade your Lightroom 4 catalog to Lightroom CC version and will take over all the previews along with edits to Lightroom CC.
Let us know if you have any further queries.
Thank you Chetna I will make the purchase.
Shootistbond007:Thanks very much for the feedback.