1) Can I file a Cheating case against him even though the transaction happend outside India?
If you have evidences for having lent the money to him, you first issue a legal demand notice to him mentioning that he has borrowed the money on so and so date but has not returned the same even after several communications through emails though he has acknowledged the liability in one of the emails. You can send this notice through a lawyer by registered post, giving him time to comply with the demand made, after which you can lodge a complaint with the police within his jurisdiction.
2) Will Bank transaction statements and email statements accepted as valid proof in court?
The bank transaction statement and email correspondences can be held as valid proof.
3) Will I get any help from Police CyberCell to trace him out and get more details about him?
This is not a cyber crime, so there is no complaint maintainable with the cyber crime police.