Looking for someone with Guinea Hen experience

My husband is trying to convince me that we should get Guinea Hens to help keep the tick population around our property down. I have a few concerns, and was hoping someone would be able to answer my questions:
Will they dig up my plants?
We have a pool, do they like to swim? I really don't want chickens in my pool.
How hard is it to take care of them? (I already have three little boys and two cats, and feel like already about to lose it).
Do you need a special permit or something like that to have farm animals on your property?

Thanks so much!
--Pam