Hello,
here are the answers:

Ad 1. Yes.

Ad 2. Yes there are examples in VB6 (not really any "usable" application, but smaller examples that show the typical tasks needed). If you install the product (do not forget to check "COM development" when selecting the installation route), the VB6 example are installed as well, and you can access them from the Start menu or the QuickOPC Launcher application.

Most examples are available for OPC UA; a couple of them for OPC "Classic" too.

We will help if you need to make something work in VB6 but is not clear.

Ad 3. See kb.opclabs.com/Versions ; the current version is QuickOPC 2018.3, and there is a column in the table for Operating System (earlier QuickOPC versions are still available for download, if needed e.g. to run on earlier systems, but we no longer make fixes to them and cannot support them).

Best regards

From: OPC Labs Contact Form - M.
Sent: Thursday, November 15, 2018 4:31 PM
To: Z.
Subject: OPC Labs Contact Form - QuickOPC and vb6

[...]
Good morning,

We have a plan to use QuickOPC to connect client appplications written in Microsoft VB6 to an OPC server. I have the following question

1. Does QuickOPC support Microsoft VB6?

2. Do you have VB6 example applications using QuickOPC? If so how can we get them.

3. Which Windows Operating systems are supported by QuickOPC?

Best regards,
M.