Hi @djf
For an enterprise your size, Connect seems to be much more expensive than Server (of course it does everything you're looking for). They have a lightweight Cloud service for academic use that has some of the features, but a hard cap of 1GB on all packages and data.
Check with their sales folk, but I'm pretty sure the IDE is web based.
Sale can also tell you about single-server hardware requirements, but they do offer a $10K/year option for multi-node setup. There's also a 5K/year package server to keep all the packages up-to-date. One would hope that includes version conflicts checks. If it does, it could save a FTE!
If you find yourself between single-server and distributed processing, consider an AWS EC2 instance. They have sizes big enough to run air traffic control systems!
Don't forget github enterprise server for backup/versioning/collaborate coding.
Good luck!