In order to retain the developed film, is it recommended to put the developed together with the camera/lens inside a dry box?
Also, a stupid question: for a developed film, which side of the film should not be touched? (front or back?)
The longevity of developed photographic film is a variable. This depends on the quality of the processing. If the process is well done, the fixing step has gone to completion and there will be no unexposed, thus undeveloped silver salt crystals. If fixing is incomplete, these crystals will in time self-reduce and blacken. If present in quality, the blackening fades the image. Next the film must be washed sufficiently to purge the emulsion of residual chemicals. Residual fixer contains sulfur which in time will attack the metallic silver image. Instead of prolonged washing, hypo (nickname for fixer solution) clearing bath is used followed by a short water rinse. If these steps are followed, the film will have archival status, good for 100 years. Best if processed film is stored in a cool dark dry location.
As to lens storage: Best if stored in a container with a desiccant. You buy some at a hardware store. In lieu of, use rice in a cloth bag. Lenses of the past were assembled with some of the lens elements cemented together with Canadian Balsam cement. This is a natural clear resin of the pine tree. This cement was used because of its optical properties; however, it is a culture media for mold and mildew. Modern optics are cemented with adhesive that does not readily promote biological growth.
Photo film is over coated with a clear gelatin layer that acts to protect however it is suitable to fingerprints. Most often the oils in the fingerprints permanently harm as they produce a relief pattern. We are taking about the emulsion side, the side that faces the camera lens. This side is identifiable if you examine the film, by reflected light. The emulsion side is dull compared the to base side that has a luster. Most often the base side as it has a balance coat. This can also be gelatin. The purpose of the balance coat is to give the base side a confident of expansion and contraction about equal to the emulsion side. The balance coat thus reduces curl as the emulsion shrinks down upon drying. Best not to fingerprint also.