Yes, you have to pay a deposit to reserve a seat. No other schools cannot see it. Yes, you can deposit at multiple schools and weigh all options.
However, there is a final date (like may 1st - cant remember for sure) that you have to select 1 school and withdraw from all others; after that date, your name and where you hold a seat at is available to all school that you are holding acceptances to. If after this date, you still hold multiple seats, schools can rescind your offer which is why it is strongly encouraged you pick one by that date.