Concerning the thunderbolt/miniDisplayPort,
You won't have to "choose between a monitor and external peripherals", don't you see? When you plug in your ACD to the thunderbolt port (you know, the new one you just bought to replace your old ACD that doesn't support thunderbolt), then you can use the ports on the side of the monitor for your peripherals. It's so simple! Just make sure you don't deviate from the Apple path!
You won't have to "choose between a monitor and external peripherals", don't you see? When you plug in your ACD to the thunderbolt port (you know, the new one you just bought to replace your old ACD that doesn't support thunderbolt), then you can use the ports on the side of the monitor for your peripherals. It's so simple! Just make sure you don't deviate from the Apple path!