Stop worrying, all concerns already solved by others to accomplish exactly as you hope:
The big considerations are exporting and testing your Samsung's SLIC bin, someone else incorrectly asserted Windows 8 only includes drivers for the included hardware and it is the opposite since Windows installation media grows because of all the legacy hardware support that is one of the few reasons Windows is attractive for wide range of hardware support.
Windows virtual driver support isn't an issue whether ancient versions of vMWare or cranky Hyper-v, the devices are always more generic and never a problem for Windows Plug n' Play / hardware AutoDetect.
You can extract your existing Windows Serial Number with lots of things like Nirsoft Produkey that is a single file executable, no installation and free at Nirsoft.net. You'll probably need it at first run of virtualized 8 that will scream about new hardware and demand a re-entry but not an issue.
Regarding your concern about resorting to old 8 once Ubuntu is installed, you already know that imaging is the better way to freeze dry your currently running Win8, but advanced format drives makes is harder if still using a Binary Research copy of Ghost 2 from the floppy, Macrium Reflect free edition seems capable of working with most AF drives even when Paragon or Acronis chokes, try it to verify it images your entire HDD.