Is WhatsApp available for PC?
No, WhatsApp is not officially released for Microsoft Windows. There is an alternative client called Wassapp but it's not recommended because it has been reported to be fake. Try to install Bluestacks then you can install WhatsApp. You might need to have your phone nearby to enter the code received through SMS.
You can manually download WhatsApp for Bluestacks using this direct download URL: http://www.whatsapp.com/android/current/WhatsApp.apk
No. Whatsapp doesn't have a pc client per say, but you can have it on your Windows pc using a android emulator like BlueStacks.
If you're using an iPhone and want to extract and read the chat logs on your PC or Mac, you can use WhatsApp Pocket instead.