Why BCHS? Because the open Internet is damn inhospitable.
OpenBSD. Documentation. Security. Reliable six-month releases. It takes the guess-work out of your environment.
Resources: man pages, FAQ, Absolute OpenBSD.
C is a straightforward, non-mustachioed language. It has full access to the kernel's system calls and a massive set of development tools.
Resources: The C Programming Language, gcc(1) (with gcc-local(1)) and nwo clang(1) (with clang-local(1)).
OpenBSD's home-grown web server. If you need more features for your web application, start rethinking.
Resources: httpd(8), httpd.conf(5), slowcgi(8), Relayd and Httpd Mastery.
SQLite is a
self-contained, embeddable, zero-configurationdatabase. It's available on pretty much any system. On OpenBSD, it's a package.
Resources: API reference (or convert to manpages) and SQL reference, ksql(3).
Install, fire up the web server, and get to work. What next? Consider your tools.