Could you please elaborate on the point you made about the artists sharing my enthusiasm for the project? Is that doable? I doubt a pro artist will get excited in a commission. In fact what I am simply asking of him is to deliver the quality that made me wish to hire his skill, in a reasonable agreed timeframe.
Well, when I freelanced for Marvel and DC (for example) I was enthusiastic about the books that I was inking. That goes a long way in work-made-for-hire.
If the project is more of a team-up between creators or even with an artist and writer owning the property, then you would want to make sure that your partner is as passionate about the project. If not, then he/she could leave the book and leave you hanging, or even renege on any past agreements.
In this later case, you might want to check out The Kenmore and Nihilist-Man Team-up story agreement/contract
that Brandon J. Carr and I put together.
Also what are the further issues that may rise if it is a work-for-hire situation?
Wow… that’s a whole can of worms. You’ll have to make decisions in regards to ownership (trademark and copyright), the return of artwork, (re)printing rights, merchandising compensation (if there will end up be any), and any other types of royalties.
Check out Ya Can't Erase Ink: The Creator’s Bill of Rights webpage
to letters and correspondence between a bunch of us concerning work-made-for-hire. (The Neil Gaiman vs. Todd McFarlane feud alone will open you eyes.)