Can my Early 2013 15" MacBook Pro connect to a 30" Apple Cinema Display... or two?
Theoretically, yes.

From https://everymac.com/systems/apple/macbook_pro/specs/macbook-pro-core-i7-2.4-15-early-2013-retina-display-specs.html: 

This model supports a simultaneous maximum resolution up to 2560x1600 on two external displays via Thunderbolt. Alternately, it can support a single display up to 2560x1600 via Thunderbolt and a single display up to 1920x1200 via HDMI. Although it can theoretically power all three external displays, as confirmed by a helpful reader, it runs too hot with three displays connected.