OC is legal in all parts of the state except city/county of Denver. Signs have no force of law, but if asked best to leave rather than be trespassed. Generally you won't be bothered, though you may get some stink-eyes. If a LEO stops you, just politely remind them that OC is legal and no permit is required. As for CC, if you're permit is recognized, you're fine. Just know the standard no gun places.
As for shooting, once you hit national forest, you're in a wide open shooting range. If you're ok with that kind of thing. Generally stay 100yds away from campsites, roads, lakes, and streams and you're good. Know your backstop and what's behind.
Official ranges? There aren't many. Mostly sporting clays stuff up in the touristy areas. There is a range in Idaho Springs, but I don't know the specifics. You'll be sort of close to the Leadville gun club, but you may have to be a member there.
Not real helpful, but it's becoming more difficult in CO to find a range that is worth the trip. Most locals who don't mind the drive just find a place in the hills and plink away. Well, that's what I did when I lived there.