For doing the transfer, you should do acclimation, like it is something new going into the tank. Your water chemistry is likely going to be different from one tank to the other - as is the temperature.
Carbon - you should run it. It helps clear up the water, and as long as you are using good grade stuff, will not harm your tank. I run a reactor that holds a ton (I buy carbon by the 5 gallon bucket - about every 6-8 months) for our 270 gallon tank (system volume about 400 gallons).
Also, meeting is the 12th, not 19th this month.

I'm sure we can discuss what to do with the sump at the meeting if you can wait until then. Getting opinions from a number of people is always beneficial. You have options, either an overflow on the main to drop water to the sump, or drilling the tank for a drain. Several of us here have experience drilling tanks.