Can some IAFs be skipped if more than one IAF exists?
Any initial approach fix (IAF) is a valid point at which an aircraft can start the procedure. Many procedures also have IAFs on multiple paths to choose from to get to the final approach. Standard Terminal Arrivals (STARs) sometimes include a certain IAF so that pilots can go straight from the arrival to the approach. Aircraft not on one of these STARs could use any other IAF.

Aircraft can also start even later in the procedure at an intermediate fix (IF), such as TELEX in the above example, provided it is coordinated with ATC and certain conditions are met.

After entering a procedure, aircraft are expected to fly the procedure as published. While it's not as common as with a SID or a STAR, ATC could certainly give an aircraft instructions for a shortcut on an approach, for traffic or other reasons. ATC would need to authorize this to ensure clearance from traffic and obstacles and compliance with restrictions such as noise abatement.