Is there an Open OPC control out there?

Hi, A) Is there an open OPC UA control in VB.NET Windows Form Application to safely - and easily in some extent - communicate with standard industrial machineries over LAN? I remember IOComp had some expensive controls back in 90's are they supported? IEC does some serious hotfixes for decades, plus is there a manual or examples to learn? I'm a try/fail pursuer.

B) For topology enthusiasts, can a TCP/IP LAN communicators (consider a simple duplex chat app) have a "Master" (Serves as a server: Gives all other nodes bulky string data) and lots of "Redundants" (Serve as clients: Get data from master and display only). In case of missing Master node, other Redundants (based on IP increment or something else) negotiate and choose one of them as their Master. Is it even possible? I'm not sure being a UDP since broadcasting is easier here.

C) In a normal scenario communication you might use your own free-port like 54321 on dedicated socket right? For database backup/restore you pass *.accdb or *.mdb to other computers via FTP (Port 21) instead of your regular port?