The Latin word for the word pool is stagnum. The Italian word for pool is piscina, in Greek pisina, and in Danish it is said as pool.
Poole is derived from a corruption of the Celtic word bol and/or the Old English word pool denoting a place near a pool or creek. The last name is likely English in origin.
pool already is an English word.
From the pool
pool carpool swimming pool pool house
In a word - NO.
A geothermal pool is called a reservoir.
Call a reputable pool builder in your area and ask if a technician can come out and do a "pool school" for you.
Billiards.
piscina
pool, lagoon
Probabily the ground surrounding your pool if its in-ground. In an above-ground pool they most likely fly into the pool or crawl into it from the sides.