Do you have a usb keyboard?
If not you may need to borrow one:
Yes you can use that.
Not really sorry
Oh I thought you meant you had a PC keyboard. No you need a a keyboard to do this. If when you get to number 6 and you do not hear the startup chime again then the keys aren't working.
Until you hear the startup chime again but if it is not working you won't hear it
The hard drive may have failed but without a working keyboard I can't tell
You can use Target Disk mode if they both have Firewire and you have a cable.
Could be. https://support.apple.com/kb/PH10725?locale=en_US
If you can start up using Target Disk mode then you can check the drive on the other computer
I can't say without the keyboard to test it