What hose clamps do I need for this?

You'll need one clamp for the 3-inch end and one for the 4-inch end. Spring clamps, worm drive, or band clamps all work — just match the clamp range to each diameter. Pick up whatever fits your budget and installation style.

Can I bend this hose further after I install it, or is the 90-degree bend fixed?

The 90-degree angle is pre-formed, but silicone is flexible enough to adjust slightly during test-fit if you need a gentle correction. Don't try to add sharp kinks beyond the existing bend — the hose works best when routed along its designed path.

Will this work with coolant, or is it for air intake only?

Silicone handles coolant, oil, and other fluids without degradation. It's suitable for cooling loops, fuel lines (where regulations allow), and intake ducting — choose your clamp type and routing based on the specific fluid and pressure in your system.