1. That is a limitation of the home (free) program, the Pro version doesn't have this restriction and has a much more configurable list of options. Whilst this is a bit of a pain the first time you might run it if you have malware in your system, after a short time, once cleaned those restrictions are less of an issue as the resident scanners catch new infections. So you shouldn't be troubled by the interactive requirement of the home (free) version, the programmers have to eat
2. The Enhanced User Interface is only available for the Pro version and where those once additional configurations live.
3. Which splash screen, when does it appear ?
4. It does remember the sensitivity and if archives are to be scanned but, because there are multiple options, Local disk, Folder Selection or Removable media, that isn't saved. So all you need do is click the local disks and the start button, assuming you don't want to change the sensitivity or archive settings.