WhatsApp Group Exporter by Codegena comes with all the necessary features that you'll need.
Yes, WAXP doesn't break the WhatsApp Terms & Conditions to the best of my knowledge.
WAXP is supported on Firefox and all Chromium browsers.
WAXP extracts all contacts from the webpage and not directly from the WhatsApp's local database. Thus, an active group can tamper the scraping process. However, this is momentary and instant mode will continue to work as soon the group is still.
No, however you can import the CSV to Google Contacts and export a vCard from there.
Go to contacts.google.com and import the CSV file to load all the contacts. If sync is enabled, these contacts would show up on your phone. If not, download the Google Contacts application on your phone.
As mentioned earlier, WAXP is a scraping tool, so some contacts may get lost in the process. If it happens to you, simply re-run the process.
Or shoot me your questions and I'll be happy to assist you.