No issues as far as pressure is concerned. Think about it: As soon as the cabin pressure increases in after landing, it's like you're going on a shallow dive. According to wikipedia, "At a cruising altitude of 12,000 metres (39,000 ft), a Boeing 767's cabin will be pressurized to an altitude of 2,100 metres (6,900 ft)." The cabin pressure is 0.78 atmospheres. So landing in that airplane is essentially increasing your ambient pressure to 1 atmosphere, provided you land more or less at sea level.
You can think of this as doing a dive where your ambient pressure increases by the same amount, 0.22 atmospheres. Therefore, as far as nitrogen saturation in your tissues is concerned, descending in an airplane to sea level is the same as doing a dive at sea level to a depth of 2.2 meters. (Remember that water pressure increases by one atmosphere for every ten meters.) Conversely, you can think of boarding and ascending in an airplane as doing a really loooooong dive at the bottom of a 6-ft swimming pool and ascending to the surface. But the point is that unlike flying AFTER diving, where excess nitrogen is released from your tissues and can potentially form bubbles, flying BEFORE diving is like descending during a dive. Nitrogen is forced INTO your tissues, not coming OUT of your tissues. That is also the reason why you can descend as fast as you like on any given dive but coming up is where you have to watch your speed. I hope this makes sense.
As for the hydration issue, I heard from a DAN physician that the latest scientific evidence actually points to slight dehydration DECREASING the risk of DCI. The jury is still out on that and more conclusive data are needed, but according to that source, there is absolutely no data whatsoever to support our notion that being dehydrated increases risk of DCI. We all preach this amongst ourselves, myself included, but apparently there are not actual data to back up that claim. I still like to be well hydrated before diving because I simply feel better that way.
Enjoy your trip!