Full disk-encryption question

[lester29]

Hi

I need to set up full disk encryption of the linux in my laptop.
Questions:

1. Does an encryption key on the USB protect against rubber-hose 
cryptanalysis?
2. Is it true that key on pendrive is more risky than password because 
someone can steal the usb key and access data without the need of password?
3. What do you think about simply encrypting the disk with LUKS and do 
encrypted backups?

Thank you, lester29