sql server – SSMS – SQL Execution Plans

I am new to SQL execution plans and I’m trying to learn more about them.

I have a few questions.

How long does a SQL Execution Plan stay in memory? If I disconnect my connection, I assume it won’t be available next time? Is there any way to change this?
Can I export an Execution Plan and load it to memory the next time I reconnect to SQL Server to bypass the Query Optimizer and save time?