I think first and foremost you should acquire a keyboard with functioning punctuation keys. It'll make your posts much less painful to read, and make you look "smarter than a third grader"
A "Hot Tank" is basically the parts cleaning equivalent of a dishwasher. Any decent machine shop should have one. And should only charge a small fee to clean whatever will fit inside. However, to the best of my knowledge, it's best for removing grease/grime and not necessarily rust. But I suppose it would depend on the chemicals that's used. You can consult the shop on what it will, or will not, remove.
If it does remove the surface rust you have, what you're basically left with is a bare metal part, which will flash rust if left unprotected anyway.
My suggestion would be, if it's very light surface rust... save your money. Even a brand new tank will develop some surface rust if not kept full on a regular basis. A new "in tank filter" and/or an inline filter would be a cheaper/easier investment
