The account details are on the front of the cheque, so I can't see what that would do.
You can't guarantee cheque clearance. You wait for it to be cleared before releasing the goods - and even then it can come back to bite you if the cheque is forged/stolen.
You can't guarantee the cheque - that story's baloney.
Cheques are only considered guaranteed if the payee (i.e. the shop) use a valid card to guarantee it so even posting a cheque with valid cheque guarantee card details on the back doesn't satisfy the rules.