If it were RM2K3 then you'd be able to call that event to move.

Unfortunately, RMXP had a lot of the good events cut out, so you'll have to make do with a switch in the event with the dialogue turning ON, and give the NPC event a precondition of Switch [0001] ON (choose the switch number that you turned on in the dialogue event, of course -- ie if you turned on Switch [0527] then you need the precondition to be Switch [0527]), or have a conditional branch:

If Switch [0001] ON
<> NPC Move
Else
<>

I think for them to say something when you talk to them needs two pages - first can be set off by action key, second automatically:

Page 1 Precon.: Switch [0002] ON (put a switch at the end of moving the NPC in the first bit of code:

If Switch [0001] ON
<> NPC Move
<> Switch [0002] ON)

Page 2 Precon.: Switch [0001] ON

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If it doesn't work, then just wait around for a while until someone pops up to disprove me.