We want to integrate Joomla/CB with our marketing automation system (actonsoftware.com). We want the user data for users that sign up for our CB site to also be in our marketing automation system so we can do things like send them a welcome aboard email, and an email a week later telling them about or forums, then another one about a webinar they can attend, etc.

The typical way for this to happen is that acton actually imports your website's signup form & creates their own form. Users then sign up on THAT form, and that form then double-posts its results back to the original form. That way user data is in both places.

The problem is that when we imported the form, we got all kinds of hidden fields like:
force_session
jabbfa63643.... (apparently some random number)
id
gid
op2
and a bunch of others (I attached a screenshot of them in case you're curious)

Short version is that when the 3rd party form tried to post to the CB form, it didn't work.

Are there some security features or something that I am not understanding?

This is really important for us to make work. I'm willing to pay a consultant to figure this out if there's one out there.

Yeah the issue you're going to run into is the security hash, I built a custom form several months ago and got some help from krileon on here with that, try going to my profile and looking up my past threads to see if you can find the ones on that, might point you in the right direction.