Queries in the shared pool

Hello everybody,

I have some questions about queries in the shared pool.

What is the better way to see how many queries I have in my shared pool on Oracle Database 11.2.0.3, count from v$sql or count from v$sqlarea?

and... Restarting the database is the same way if I flush shared pool?

I ask because I need to perform an upgrade from 11.2.0.3 to 12.2.0.1 and I need be careful because I need to avoid issue performance after the upgrade.

So if the upgrade executes a database restart automatically, May I say the shared pool will do a flush anyway and all queries will make a hard parse after the upgrade?