In response to the points raised.
1. The taxes would be initially used to set up a database of copyrights and keep it up (no argument about funding - it's self funding).
2. This depends on the meaning of profit. The IRS is the biggest "profit" producing part of the government. If the excess funds are placed in the general fund, it's not a "profit" producing part of the government.
3. The point to remember about copyright, it is a limited, wasting, asset. It does not have to follow the same rules of real property. There's separate definition in the constitution.
Finally, extra funds from the copyrights could be used for copyright enforcement.