Do I need clamps for both ends, and what size?

Yes, you'll need hose clamps at both the 2.50" and 2.75" ends. Pick clamp sizes that match those diameters — most builders use standard stainless steel or spring clamps rated for coolant or boost applications.

Can this handle coolant and boost lines interchangeably?

The 3-ply silicone is rated for both coolant and low-to-moderate boost pressure. If you're running high-boost applications, verify pressure limits match your system specs before install.

Does this hose come pre-cut to a specific length?

This is a full-length reducer hose. Measure your application before ordering — you may need to trim or cut it to fit your exact intake or cooling routing, or source a shorter variant if your run is shorter than stock length.