Adding files to a review process

Hello, fairly new to Adobe Sign.  We send out documents to get signed and then they come back to me to review.  Is there an option in Adobe Sign that I can add a file during my review process or does that need to be set up when sending out the document?

Also, when we send out documents that need a file attached, is there an option for the signer not to sign unless he/she has the attachment attached?

Thanks.

RS