Comp package consultant to advise startup exec candidates?

That's a great question. I hope I understood it properly.

In terms of the comp landscape, tools like glassdoor.com are great for finding market value salaries for specific titles/locations. No need to hire someone there.

For the rest, it seems like the expertise would be spread between an HR exec, or a CEO. I'd recommend reaching out to retired CEOs who are in mentorship programs at local incubators. They've been there and done that, so they know what goes into negotiating and retaining folks. They're used to walking through these types of challenges with startups.

If this is a one-time thing, I'd be happy to hop on a call to talk about these challenges as well.

An HR Consultant can help you form a compensation plan and package supported by job descriptions. You should also have clear job offer letters and an employee handbook.
The HR consultant should be able to reach for you (or know) lots of data on salary by position, benefits offered, etc. They can coordinate with vendors to get you lined up to support the on-boarding of the employees.

The job descriptions should be detailed so you can be clear on what sort of work is within the role, what kind of qualifications you expect in the candidates, etc. This will in turn move toward goal setting with the employee as you develop a working relationship and they get comfortable in the role.

The compensation part is easy, just don't forget that you get what you pay for and geography and industry count for a whole lot. Tech in Nor Cal for example, is a very hot market for comp and competing with the larger employees here takes some serious comp plans.

Compensation can also be substantially different in structure from one job to the next. Say, a VP of sales vs a product manager, or software engineer.

I can help :-)