Also, you probably want to pick some community to affix to all routes you learn from your customers / originate yourself, and to make sure isn't affixed to rout

Also, you probably want to pick some community to affix to all routes you learn from your customers / originate yourself, and to make sure isn't affixed to routes you learn from your upstreams, so that you can then have a route map check for the presence or absence of that community when deciding which routes get passed along to your upstreams. (BGP doesn't directly solve the problem that an AS doesn't carry traffic unless the source and/or destination is ultimately a customer of that AS, it just provides mechanisms that can be used to make that happen.) You may want to define communities to let your customers selectively decide to suppress announcements to each of your upstreams, and you may want to pass through the communties recognized by your upstreams in their official documentation if your customers send those communities to you, if you want to let your customers control their advertisements in that fashion. (The only reason I can think of you wouldn't want to let your customers do this is if it would let them move traffic from a link that's cheap for you to a link that's expensive for you.)