Hi!
Thank you for your questions. This board is the perfect place for asking questions.
1a. UltiDev is wrapping up development of the new much more advanced UltiDev Web Server Pro, which will be made available as a first Beta in a few weeks. It will remain free, lightweight and redistributable. It will be much more suitable for hosting Internet-facing sites and applications, designed to be more resilient, support virtual directories, port sharing, compression, features isolated host process, can run 32-bit applications on x64 systems, supports ASP.NET 4, etc. We'll release a one or two more Betas followed by the production release in Q1-Q2. We committed to keep it free of charge and do not make UltiDev Web Server a part of our direct revenue source.
1b. If UltiDev or its successor decides to stop developing the web server, we'll open source it, but the product is popular and relatively low-maintenance, so we have no plans to stop supporting it.
2. It's a number of known net installations of the product, meaning number of installations minus of number of uninstallations. Our product sends home its SKU and +1 or -1 when it gets installed or uninstalled, so we can know for sure how valuable (or not) what we do. So the number is pretty reliable. As of today it's 517,000 net installations (717,000 installation minus 220,000 uninstallations) worldwide. It includes installations of our web server bundled with 3rd party software.
Best regards,
UltiDev Team.
Please donate at
http://www.ultidev.com/products/Donate.aspx to help us improve our products.