Gameplay style, type(s) of work; sprites, animations, tiles, props, backgrounds, UI, etc, specify everything you need. Artists don't like to be surprised by new demands mid-project xP

Sizes of the various assets. For animations, the number of animations and how many frames you expect them to be or how smooth you want them to look. Size has a huge effect on workload (and thus price) when it comes to pixel art.
All of this information can be approximate, of course! You can also provide examples of other games with a similar look to what you want, just make sure you specify what it is about those games that matches what you want.

If you're open to working with multiple artists, mention that! Many artists can't commit to doing all the art, or may prefer to do a particular type of art, and if your post sounds like you expect one person to do everything when that's not the case might scare off some great candidates. However, do keep in mind that working with multiple artists may lead to a less coherent look for your game.

2. Going rates:

Anywhere between $10/h to $50+/h, depending on the skill and experience of the artist. I recommend reading https://pixelation.org/index.php?topic=23286 - this guide ( https://pixelation.org/index.php?topic=23286 ) to get an idea of how pixel artists (should) price their work.

Future "opportunities" mean very little to most artists. The possibility of a job at a studio that might be successful one day doesn't pay the bills now xP So, don't bother with that, instead focus on compensating your artist now, don't make them take unnecessary risks.

Similarly, revenue share is typically not desirable since it's not something artists can rely on. Rev-share is only really acceptable if you're already big enough that you can almost guarantee a significant enough profit. Normally, rev share is something people do when they're equal partners in the project from the very beginning, not when one person is hiring another.

3. Company info:

You do NOT need to have a company established, don't worry! Provide some information about yourself and your goals with the project instead. Specify that you're an indie developer, and mention that you plan to crowd-fund, and how/when you intend to pay the artist.

4. Information about yourself:

What's your goal with the project, why do you want to make it? If an artist shares your vision, they'll be more excited to work on it with you, which will lead to better work, and perhaps even a lower rate (but don't count on it - passion doesn't pay the rent).
What do you contribute to the project? Savvy artists know to be wary of people who try to put together a team but do nothing significant themselves xP Alleviate those fears by explaining your role.

You should also mention what country or at least time zone you're in, and what language(s) you prefer to speak, as these can have a significant impact on the artist's ability to communicate with you effectively.

5. Starting place:

Here is fine, if you want pixel art specifically. Pixelation is another good place. You may also want to try TIGForums and other websites frequented by indie devs and pixel artists. Twitter's also great for finding collaborators, as long as you grow your presence and audience there organically for a while before making job postings. It's never too early to have a Twitter presence for yourself and your projects!

There are plenty of first-time devs posting here and in these other places, and the fact that you're going out of your way to figure out how to make the best impression already puts you way ahead of many of the other job postings on most of these sites xP