I disagree with getting Warmog's as a first item because it doesn't contribute anything to your midgame. It gives you a bit more survivability, but you shouldn't be tanking midgame anyway. Tank Cho is straight-up bad, his mana requirements for his initiation skills are too high and his tanking hinges on him not dying, so he can't be a fearless "run in and initiate" champ like malphite or amumu. In general AP is better, and if you think otherwise you're playing at a low ELO where it doesn't matter what you do because feeders gonna feed.

Don't read the MF Chogath guide if you're any good with Cho. If you have no idea how to play Cho it's not a bad read, but the build he plays is pretty bad, people only like it because it was posted on the LoL forums and there are a bunch of huge noobs there who screamed because it was entertaining.

Runes. You have 9 runes per clas (not counting quintesences) a minor fix to add.

Also Shroud as 1st item is kinda hard to complete. Some lower lvl item and boots would be recomended before shroud.
I like Chalice of Harmony for additional MRes and superb mana regen so you could spam Rupture and scream.

Whats up with Heal on Tanks?

The runes are theoretical, it's not what you have but what you suggest. I personally recommened using your own runes but if you don't got all of them just pretend you do. When it comes to the mastery build I would rather have 3 extra points into Evasion instead of harden skin, also you fail epicly by putting up scream instead of Vorpal Spikes.

Vorpal Spikes outdamage and makes it easier to farm than adding more points into Scream.

PS: Too short Description, you're setting up a spam build... it's -1 by default.