no most of the time you don't even feel them on you. however if you notice a leech is sucking on you and try to pull it off normally, it may rip the skin and get infected (that would hurt!) if you see a leech on your skin here is the proper way to remove it... if the way listed below does not appeal to you, you can always burn them off instead :)
No they do not
No, leaches are from Phylum Annelida and Class Hirudinea, which is completely separate from Phylum Mollusca.
go on the internetfind out what you needgo buy the stuff you needgo kill the leaches
No
leaches
you could drain the pool, but if you don't want to drain your pool, you could get a pool skimmer and get all of the leaches out of your pool and then carry the leaches to a near by sewer, or a murky pond/lake/river.
No, they are invertebrate creatures.
Yes, blood.
yes
yes
They thought there were "vapers" in the blood so they used leaches to remove them.
They get brittle