What size hose clamps do I need for this?

Standard worm-gear or T-bolt clamps in 2.75" diameter range work here. Measure your existing clamp or go up one size from your 2.5" setup—most shops stock them. Hand-tight plus a quarter turn is plenty; over-clamping silicone can damage the material.

Can I use this for fuel lines?

No. Silicone hose is rated for coolant, vacuum, and boost applications. Fuel requires braided stainless or fuel-specific hose to meet safety and permeation standards.

Do I need to prep or cure this before installing?

Not required. Use it straight out of the box. If you're concerned about initial odor or residue, a quick rinse with water and air-dry won't hurt, but it's optional.