Hiding AND Pre-Populating Certain Fields on Signup Forms

To preface this issue, I want to say that I'm aware that there are various ways to go about doing any one of the following on their own and I will try to explain my process for each use case requirement. I'm looking to achieve a specific combination of features, and I'm hoping there's a way to do it with this module but I'm not sure whether I'm just unaware of how to get it set up. Also I know that there are various threads out there relating to a couple of my use case needs, but I haven't been able to find anything that speaks to all the specific things I'm about to outline; please point me in the right direction if this ends up being a duplication.

Here's a description of my use case requirements:

1. I need to create a signup form that allows me to turn off the double opt-in requirement because of the particular audience that will be using the form
Drupal Mailchimp has this feature built-in, and I understand that I could also achieve this functionality by going custom via the API (which I can't do for unrelated reasons).

2. I need to be able to pre-populate certain fields on my form for tracking and segmentation purposes
I have been able to do this with custom/embedded/self-hosted forms. However, for this particular project, this route won't work because it conflicts with my need to remove the double opt-in requirement (again, unless I go custom via the API). I haven't been able to figure out how to pre-populate my interest group fields with the Drupal Mailchimp module.

3. I need to be able to hide certain fields on my form, including some of the pre-populated fields
I can customize the embedded/self-hosted forms from Mailchimp to achieve this functionality (again I ran into the double opt-in thing), and I have seen a thread where it was suggested to use custom CSS to hide certain fields with Drupal Mailchimp, but I can't find how to hide pre-populated fields via this module.
As a side note, it would ideally be handy to be able to have Drupal use a token for the hidden fields (subscribe source = current Drupal path/URL). However this last bit isn't totally necessary since static values would suffice for my needs. The real struggle I'm running into is I can't figure out how to specify a default value for certain fields (interest groups). I think if I were able to do that, I would be able to just customize my CSS to hide those fields...Is that correct?

4. I'd really like to be able to integrate my signup form with CRM Core
Ultimately this last one might be out of place, and I'm aware that CRM Core Profile can give me some of the functionality I need, but I'm unsure how to either connect my CRM Core Profile form to add entries to my Mailchimp list, or get my Mailchimp signup form to add entries to CRM Core. I'm not as worried about this particular piece right now, but if anyone has any answers/thoughts on this, I'd really appreciate the help.

Sorry for the long explanation but hopefully it helps provide a context for what I'm looking for, since again I know there are similar issues out there but none of them quite cover what I'm looking for. Basically, what it comes down to is that I want to be able to use the Drupal Mailchimp module (hoping to avoid having to go custom/API) to pre-populate certain fields (specifically, interest groups) as well as be able to hide those fields (whether via custom CSS or if the module has some feature I haven't been able to find that allows hiding fields). And as added icing on the cake, if I could figure out how to get CRM Core and Drupal Mailchimp to communicate directly/share info, I'd be just tickled pink.

If anyone has any thoughts or help to provide, I'd be much obliged!!