Will this work for coolant, boost, and vacuum lines?

Yes. Silicone handles coolant temps, turbo boost pressure, and vacuum duty without degradation. Confirm your specific application's pressure and temperature limits match silicone's rating before installation.

Do I need clamps to secure this hose?

This hose elbow assembly only — clamps sold separately. Standard worm-gear or spring clamps work with 3.50" bore. Torque per your vehicle's service manual or clamp manufacturer specs.

Can I use this hose on a tight-radius bend instead of the 90-degree?

Not recommended. The 90-degree shape is engineered for that specific routing angle. Forcing a sharper bend will collapse the reinforced walls and shorten hose life.