Cat5 or Cat5e is plenty fine.
None of the camera's will use (or support) anything higher anyway. 30 camera's seems a bit overkill - is this a factory sized place?
Get a decent PoE switch that will support at least 150W.
I'd probably lean towards 2 x 24 ports just to make sure there is sufficient power per camera.
Budget at least 10W per camera, they'll use much less daytime (3-5W), and more at night when the IR comes on.
30 x 10 = 300W needed (likely more on startup or reboot or nighttime), so go for something with more headroom. - i.e. 4-500W total.
The Unifi series are good, and have decent management software - eg
https://store.ui.com/collections/unifi-network-switching/products/unifiswitch-24-250wI don't suggest the Unifi camera's or NVR, they're overpriced and underpar in terms of quality/bang per buck.
Camera's - 1080p is a little low res, so should be cheap. Just make sure they support ONVIF.
HIKVision, Dahua etc make plenty of options.
As for VMS - I haven't really looked into that side in much detail.
Will really depend on your requirements, i.e. what other things than basic recording are needed.