Yes, DRS is finally coming to Steam! I'll arrange the keys for itch owners after the official release.
The new version has a map button at the bottom of the service selection screen, did you notice? It's easy to miss though! There's no map during the actual run yet, this is planned for the next update.
Motion blur is perhaps the single most demanding graphical effect. Does it help if you turn that off? You might also get better performance by using the second best quality option, but still enabling some of the additional effects, rather than using the best quality and disabling some effects. The sim is nowhere near fully optimised yet so hopefully you don't need to get any new hardware!