In your passport surname is blank, then leave it as blank or type space value.

If you are coming from Singapore by road and you are not staying just one day visit, then you can enter blank address and upload an covering letter & mention that you are not staying anywhere in Malaysia. However all approvals are subject to Immigration Authority.

No, You need to upload all documents are properly scanned from Scanner Device only.

All documents should be typed from computer and scanned from Scanner device only.