Correct if you select that option.
No, shouldn’t be like that.
No, they don’t touch your price. You will get grandfathered with the chance to upgrade to new plans for cheaper or free.
Doesn’t look like it as of last year: https://productioncommunity.publicmobile.ca/t5/Get-Support/Call-Control/m-p/771729#M511754.
If you’re on Google Pixel, you can enable screening and automatic blocking. On iPhone, there’s Robokiller.
Smaller models aren’t as good as GPT