Only if the assets use relative URLs: href/src attributes that begin with a single slash ("/folder/subfolder/page") or a partial pathname (like "folder/page").
When URLs begin with double slashes // or with a protocol, they do not use the main document's hostname, they use the hostname that's explicitly present in the URL.
On Marketo-hosted LPs, assets like the Forms2 library load from a relative URL, so if the main document loads via CDN, then so do those assets, automatically.. (That's the default behavior, but it can be advantageous to change it in other scenarios that I'm getting into in an upcoming blog post.)
On non-Marketo LPs, Marketo assets can't load from a relative URL, thus even if the main document is CDNed that doesn't automatically propagate to the assets.
Gzipping dynamic assets like form descriptors can actually add more overhead (the server-side compression component is not instantaneous) than the bytes on the wire cost you in network overhead. Be aware that the response to getForm? is recomputed every single time it is requested: if this were not done, then you couldn't update a form and have the update take effect around the world instantly. I can't say whether the overhead of constant gzipping is worth saving 3500 bytes on the wire, but there's a good chance that it would work in the other direction, depending on server horsepower.
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