You could do that using CB Auto Actions. It includes an AcyMailing auto action type for subscribing users to newsletters. Something like the following should work.

Global
Triggers: onAfterUserRegistration
Type: AcyMailing
User: Automatic
Access: Everybody
Conditions
Field: SELECT_YESNO_FIELD_HERE
Operator: Equal To
Value: 1

Now you'd just configure the AcyMailing parameters as desired. You can make a second auto action to handle usergroups using the Usergroup auto action type. Note this only applies to frontend registrations. If you need it to apply to backend and profile updates you'll need to add additional triggers from the below list.

Backend
Registration = onAfterNewUser
Edit = onAfterUpdateUser

Frontend
Registration = onAfterUserRegistration
Edit = onAfterUserUpdate

1. For Value: 1. Would I put the #1 or the word Yes?

If it's a checkbox field then the values are as follows.

Yes = 1
No = 0

2. On the flip side, if the user goes in later to update the answer to No, I would want to automatically remove them from the Mailing List and/or user group. Which Auto Acttion would be ideal for a user editing their profile?

Same auto action just invert the action behavior and conditions. So if the value is 1 add the usergroup. If the value is 0 remove the usergroup. Both would be Usergroups auto actions. So to add/remove the newsletters and the usergroups you'd have a total of 4 auto actions. 2 for newsletter and 2 for usergroups.