Training Bond

I have signed a 2 year training bond for a 3 months training program with my company and I have served 1 year of my bond currently.

(1) The agreement was to compensate 2 years my current salary, is such an amount
It is an amount that in the agreement and you have agreed to it, you shall ask this question before you signed the bond. Whatever the amount, you will have to pay unless you challenge them in the court when you refuse to pay.

(2) If I were to leave 6 months earlier does it mean I have to pay only pro-rated amount (6 months of my salary)?
It depends on what have stated in the contract.

(3) I have transferred all the knowledge from the training to the new company by setting the whole department and SOPs, can they still put me liable to the training bond?
Yes. As per contract.

(4) What can I do if I was made to do jobs not in within our job scope including 1 year of cleaning work as the company refuses to hire a cleaner for a 5-floor building with 3 toilets (I was hired as an executive level). Verbally abusive and basically taking advantage of this training bond situation. What can I do about it?
You may bring this matter to MOM, but I doubt there will be effective for your case. You may choose to bring them to court to sue them under civil suit and to prove to court that they did not honor as per contract.

(5) The notice period for termination is 6 months, as long as I signed the contract, I’ll have to honor it?
If it is stated in the contract, yes, you are.