Clients set up changes and findings

Hello,

I quite new here, I have been exploring the system and some questions pop to my mind.

1. Can the clients be set and do the findings through a Company Name intead of the name of the contact person. Can I add different VATS or CIFS per company and have a summary based on them.
2. Can I add new fields in the Client profile such as VATS…
3. How can I add different taxes and select them in an invoice.
4. Can I send an email or any type of alert for invoices overdue.

I been trying to follow upo the tickets but I could, if you can show me the way I will be pleased.

Thank you so much in advance for your help,

BR,

Guillermo