First of all, trademark & copyright law are completely separate. Don't depend on any general principles to apply to both.
Second, it's probably better if you don't think in terms of "ownership". In Berne-convention signatory nations (i.e., just about all nations, including the U.S.), copyright exists in most works on their completion, with the legal author(s) holding the copyright until it expires. That would usually be the actual authors, unless it is a work for hire, in which case it is usually the employer.
So if the work is created by employees of a corporation as part of their work, and there is no contract stating to the contrary, then the issues you bring up do not arise; the corporation is the sole legal author.
In a work with multiple legal authors, all authors would have to agree to any licensing. One way to do this is for all authors to agree formally that some particular party may act as their agent in such matters. If this is not done, then, whenever any licensing or publishing issues come up, they need to be run by all authors for their approval.
As for trademarks: couldn't say.
Check out http://www.uspto.gov/trademarks/teas/initial_app.jsp
At the bottom, Collective Trademark/Servicemark Application
You can register both individually, and then execute a licensing contract for each afterward. You sign and the new party signs. Terms of the agreement ae mostly up to both of you.
Trademarks allow for extra assignment recording rights. You can check the USPTO website for those or contact an attorney for specifics.
Basically, you creat a license, like GPL or a CC license or a custom one (how most are done).
You can charge a flat fee, ongoing royalties, or other. Whatever fits your goals and the market.
atty here btw.
Depends on what you mean.
As I said in the GP, under the Berne Convention, copyright exists in a work when it is created. There is no paperwork required. For example, thousands of people hold copyright to portions of Wikipedia. The Wikimedia Foundation makes the license, and the terms under which contributions are accepted, clear, and that's it.
But if you want to be dividing up money, then you'll need to carefully consider the issues of whether the licensing terms would hold up in courts in various jurisdictions, how to prove at a later date that authors did indeed agree to the license terms, and how the licensing terms might be changed, if necessary, without all authors needing to be contacted individually. For that, you need to talk to a real lawyer (which, once again, I am not).
And then there is the issue of just how you're going to collect money and get it to all those people ....
The work required to license either isn't difficult. Arguing back and forth on terms is how the legal bills add up. It all boils down to how much money must be paid.
Your product is mostly the underlying asset, not the streamlined process.
Remember, every licensee of the copyright or trademark will be selling the same thing (mostly). How do they differentiate themselves in the market? Probably price, in a multitude of ways.