Transitioning from Mimecast to O365 Spam filtering

We’ve been using Mimecast for years, and it works well, but as we’re now using O365 primarily for email and we are on a .local domain it is getting harder to do directory sync with Mimecast now that LDAP requires encryption (yeah, we need to get that working anyway… or drop everything relying on LDAP over the WAN).

Have any of you transitioned from Mimecast to O365? Also, what documentation or tutorials would you recommend for learning what O365 has to offer? It seems like there are a variety of security offerings that are interdependent on other services and I’d hate to go in thinking it is as simple as enabling licenses and changing MX records only to learn I need to enable other services and purchase other products.