Exposed, yes probably. However all those ports were just moved around for ESB/ROTJ. On ESB they all got hidden on the back, in ROTJ all but 2 got hidden in the back.
As for the colors, these sections are 110% white on all versions that isn't ESB.
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The tanks, thrusters, and rocket are look more grey, probably SP Lettering Grey. Some people paint them silver for ROTJ but that's not correct as they are for sure gray for ROTJ and probably the other colored packs too.