connecting branch offices to head office

My Computer Server runs on Novell Netware 4.2, my bank application, BankMaster runs on DOS 75 user licence. With these platforms, I want my branch offices (4)that are located, each about 900 km away from the head office to connect remotely to this server.
1. What is the best solution for the remote connectivity?.
2. How do I implement a mini-network in the branch offices running real-time on-line and at intervals the mini-server should update the main server in the head office.
3. To implement customer remote banking from their homes, what products/solutions do I need to achieve this.

Regards