Can I add the invoicing address data as a tab in user profile?
It's stored to hidden fields, but you can try using the invoice field names in substitutions inside of a Custom HTML field. The following fields are available.
cb_subs_inv_first_name
cb_subs_inv_last_name
cb_subs_inv_payer_business_name
cb_subs_inv_address_street
cb_subs_inv_address_city
cb_subs_inv_address_state
cb_subs_inv_address_zip
cb_subs_inv_address_country
cb_subs_inv_contact_phone
cb_subs_inv_vat_number
So for example to substitute in the country you'd use [cb_subs_inv_address_country].
How do I manage them?
You're not really supposed to as they're a part of the basket process and not really the profile.