Yes, if the sandbox and production are tied up you can send data from production to sandbox.
You must have to fix the errors first in sandbox and then move it to production. Once the validation in production is successful, then only you can deploy it to production.
Generally whenever a huge changeset is transferred from the server, all the pending changesets which are submitted after that changeset, go into a hold status. Once the huge changeset is done, your other changeset will start working. Hence you must wait for couples of hours may be just for the server to free up.
You can always raise a case with salesforce. However, When there is a huge amount of metadata been transferred it takes time. I have seen cases when changeset tooks more than 6 hours to deliver. But it always reaches for sure.
It is not possible to move data using Inbound Changesets. Inbound only shows any incoming changesets to be deployed and Outbound is the one which can help us move data to other orgs.
Changeset supports almost all metadata movement. You can’t move your data with this tool but metadata like pages, classes and others can be moved.
Changesets is the best way to achieve this. Also Eclipse and Ant Migration can be used as an alternative.