Should not be a problem but nobody here can truly answer this because it is purely up to your new landlord if they will allow it or not. They have every right to require him come in person & sign.
Probably not, since hey'll want to know he really signed it. They might allow it if his signature is notarized.
No. They want to see that you're not just forging a signature..
They might allow it if he has a notary.
It depends on the landlord. There is no universal answer.
Should not be a problem.
Possibly signing a lease tomorrow but my buddy will be at work can i bring it to him to sogn then bring it back to the leasing office