I'd like to customize our registration form: add newsletter opt-in and captcha

and we'd like to add a lot more content to the login page with things like a "please login to continue" message.

Has anyone out there been able to add a mini-login to the skin? I'd like to include a username/password login in our page header.

Ok, so there are a few questions here and i will try to answer each and give you an idea where to go from here.

Q1. Can you have the login in the skin?
A1. Yes, there is a Skin object that will allow you to show the login page in a skin.  I believe the one you want is "SIGNIN".*

Q2. Can I/How Can I Customize the Page the login module is one?
A2. Yes, it is not hard to do, but you must be careful to complete the steps as outlined below.  If you set the location before the page and module is completed you will have a vary hard time logging in... 

1. Login as Admin/Host
2. Create a new page for the Login page (be sure you remove the Show in Menu check mark)
3. Add the Account Login module to the new Login page
4. Add other modules and content as desired
5. Go to Admin > Site Settings
6. Expand the "Advanced Settings" section
7. Select the newly created page with the "Login Page" drop down list
8. Click Update to save

Q3. Can I customize the registration page?
A1.  Yes and No.  You can customize the user profile information and you can turn on and off a few features like captcha, but if you really want to create a robust registration page with Opt-in, role assignments based on answer to questions, etc, you will want to use a 3rd party registration module.  I have had very good success using the UCanUse User Attributes / Registration module that you can purchase from SnowCovered.com.  It work well and is reasonably simple to use... 

*You can view all the available skin objects by going to the Host > Extensions page and scolling down to the Skin Objects section

Best Regards,

Robert J Collins | Co-Founder & President

Netlogic Corporation