The Spring 2018 update will be very cool looking if the betas are any indication. JFYI, the "Classic" theme is not available out-of-the-box with Windows 10. You probably are looking at third party software for that.
Most people do not realize that most of the telemetry can be stopped by turning off one or two services, the primary one being "Connected User Experiences and Telemetry" Most of the rest of the privacy issues can be handled via the Privacy panel of Settings. The Cortana component of Search can be turned off with a single regedit. Very little tweaking really, for an OS that is designed to be tweaked.