Using the VB CMS over VB Advanced will be a matter of opinion, but there are other advantages for buying the Suite over the Forum Only package including better support that should also figure into your decision.
As for styles, there are a number available for download in the
4.x Styles section. Style versions are more specific in 4.x then they were in older versions so you'll be best using a style that exactly matches your specific version, or at least very close to it. You wouldn't even try to use a style for 4.0.1 for example on 4.1.2.