How do I apply for a new PR Card ... old one will expire soon / or should I apply for Citizen

[Ema2000]

Hello,
My PR Card will expire soon. When should I apply for a new one and HOW do I do that?
Where can I find the link? How much will it cost?

.... or should I apply for Citizen???
Can I keep My German Passport than as well? How much does it cost to get Citizen Card? How many month before the PR Card would expire should I apply for Citizenship?

thank you
Emma