Yes, quite a bit of experience.
(Installed and maintain five sites, all using IP's, debian and zoneminder)
Zoneminder will do all you want, as will other stuff, but most of the good software tends to be quite expensive. Zoneminder is solid, proven, reliable, well featured and free. Motion is another linux app that does similar stuff, but I use zm and know it inside out.
Anyway - your assumption is wrong. IP cameras will do what you want, but so will analogue cameras - IF you go with a server combination as above. That receives the analogue or ip streams, digitises and parses/stores them in many ways. Detect movement, send emails, etc etc.
Many ip cameras will do this entirely by themselves though (Axis, Y-Cam, Panasonic etc), and depending on your needs you might not need a computer running, recording etc. I do - for 24/7 recording as well as events, but not everyone is me.
But - with 6/8 cameras, and motion detection being the unexact science it can be, you will likely get a lot of images and you might want to be able to record/sort/auto expire centrally, and if so, you need a computer running with some software to do this.
If the above doesn't answer your needs, give me a bit more info and I'll have another crack.