Do I need gaskets or seals with this manifold?

This is the manifold body only. You'll need intake gaskets to seal between the manifold and cylinder heads — these are wear items and should be replaced during installation.

Will I need to remove anything else to access the mounting bolts?

Access depends on your specific truck configuration and what's mounted nearby. Plan for removal of air cleaner assemblies, hoses, and wiring harnesses — consult your service manual for exact removal order.

Is there any prep needed before bolting this on?

Inspect the cylinder head surfaces where the manifold mounts — they should be clean and free of old gasket material. Use a gasket scraper and degreaser before installing new gaskets.