Hey guys,
Sorry for the slow reply. I've been at Gen Con for the last week! It was crazy but fun. Now that it's finally over, I can get back to regular business.
Your initial interpretation of steam powers is correct, as follows: "The way I'm reading the coglayer class description, all coglayers have access to all steam powers, from Amplifier to Wavemaker. Their only limitation is how many components they can maintain at once, as determined by level and Int modifier (and the Gearhead feat)." That's correct. The other section you refer to is flavor text that probably should have been reworded.
Keep in mind that the assumed background for a coglayer is someone who's raised on a city-mech and has access to a knowledge pool of other coglayers, Gearwrights, steamborgs, gear forests, mechs, and steam equipment. I assume that a coglayer has plenty of reference material for steam powers based on swapping stories with peers, and observing the city-mech environment he's raised in.
You could play on this in a campaign by creating coglayers from different backgrounds, or with limited exposure. For example, a peasant living in a worm tunnel deep underground might simply have a knack for steam equipment. He could end up taking a level as coglayer, but lack exposure to the wide variety of steam powers available. The DM and player could agree that he only has access to steam powers X, Y, and Z (those he developed on his own in the worm tunnels), but he can acquire others as he adventures and meets more coglayers. This obviously limits the character but makes for a cool role playing experience.
Another role playing possibility is lost or secret steam powers. A Gearwright could develop an intriguing new steam power (something the player comes up with) and the DM could rule that because it's new, knowledge of it hasn't spread yet. So the player could have access to a unique steam power -- until he uses it in front of other coglayers, of course, and they decide to copy it, and the idea spreads.
Hope that helps. As for a DragonMech forum, I'll see what I can do.