I'd like to address a few of those concerns and try to shed light on some of the mysterious things that a good tech does (or should do) to a horn.
On a newer plastic student horn, a re pad might only include dis-assembly, washing the body, quickly hand-ragging the keys, replacing missing corks, replacement of all pads, reassembly and adjustment: about a 2 1/2 hour job for about $150. For an instrument with fresh tone-holes, snug posts, tight mechanism, shiny nickel plated keys and recent springing this might be sufficient, especially if its going into the hands of an 11 year old of indifferent ability.
An overhaul, on the other hand, would include everything necessary to return the instrument to as close to 'like new' playability as is feasible (sometimes extraordinary measures are not justified by the value of the instrument), and address the preferences of the more advanced player in question. This might include: Swedging/countersinking the key-work to remove lost motion, re-facing of tone-holes to assure optimal pad seat, tightening of posts, replacement of all cork (including adjustment of opening height to regulate tone and intonation), thorough oiling of body, buffing of body, posts and keywork, polishing of the bore, straightening or leveling of bent keys, key cups and rods, realignment of keys with tone holes, replacement of weak springs, repair of small cracks or chips, installation of a mix of high quality double bladder/leather and cork pads, reassembly and adjustment, and re-gilding the logos! Total of 6-10+ hours depending on age, complexity of mechanism, and condition.
To Be Continued....