Will the 'wipe data/factory reset' option in clockworkdmod also wipe the internal sd card?
No.

This would make no sense, because the main use of wiping from ClockworkMod is to install a new ROM from SD card. As certain devices (e.g., Nexus S) do not have an external SD card, wiping the internal storage marked as "SD card" would wipe the ROM you are about to install.