New camper. Water features

Hello. In 2 days I will be taking my new (to me) 2003 Starcraft Travelstar 21rb out for our first trip.

I previously was the owner of a coleman popup..and never used all of the water features in the camper.

With this new camper we want to use it and i have a few questions.

I have not sanitized the water holding tank, so for this trip I mainly want to use it for the toilet. Questions are.
1. I do not know where or how the pump is turned on, but I assume the pump will need to be activated to flush the toilet?

Yes you need to turn on the pump prior to using the toilet or any faucets

2. When I go to dump the waste after our trip I understand to dump the black side first, and the gray side second. When I release the gray side will that also drain all the water that is still in the tank that was unused? If not how do i drain that water to empty the tank?

Makes sure the black tank is at least 2/3 full before dumping as this makes it easier for everything to come out; when you use the toilet don't skimp on the water when flushing...to drain the fresh water tank there is usually a drain valve underneath trailer to turn

3. I assume campers have 2 tanks? 1 for the fresh water you put in it, and another for the water that goes down the sink and toilet. I am guessing they are the same in size?

Not necessarily...the order usually goes the fresh water is the largest, gray tank is second and black tank is smallest

I am sure i have more questions, but if you can offer advise on these hopefully I won't have to leave the camper at 3am for the public restroom!

Thanks!!