Fit: Relationship between an external feature of size and an internal feature of size (the hole and shaft of the same type) which are to be assembled.

Transition Fit: A fit type where clearance or interference can exist between assembled parts depending on tolerance conditions.

I would like to select a face, either a flat surface, or a cylinder, and have a chamfer/radius placed at every edge of this surface.

Fits and tolerance calculator for shaft and hole tolerance calculation according to ISO 286-1 and ANSI B4.2 metric standards . The schematic representation of the fit is also drawn by tolerance calculator.

There is a way to select faces, but not the way you are describing.  In the fillet command you can pick one face and then an adjacent one, but that is cumbersome.  You can also select a feature and it will radius all edges that way, but not a face as you describe.  This looks to be a good candidate for the Inventor IdeaStation

This iLogic creates a chamfer on already chamfered edges, which is shouldn't do, but I didn't bother trying to filter those out.

The need for limits and fits for machined workpieces was brought about mainly by the requirement for interchangeability between mass produced parts. In order that fit function could be satisfied, it was found sufficient to manufacture a given workpiece so that its size lay within two permissible limits, i.e. a tolerance, this being the variation in size acceptable in manufacture while ensuring the functional fit requirements of the product. Similarly, where a specific fit condition is required between mating features of two different workpieces, it is necessary to ascribe an allowance, either positive or negative, to the nominal size to achieve the required clearance or interference.

Upper deviation: The difference between the maximum limiting size and the corresponding nominal size of a feature.

On the ribbon, click 3D Model tab  >  Show Panel icon . Select Plastic Part panel to display the Plastic Part panel, and then select Rule Fillet

ISO 286 establishes a system for tolerances to be used for linear sizes of features of cylinder and two parallel opposite surfaces. It provides a standardized selection of tolerance classes for general purposes from amongst the numerous possibilities. The main intention of this system is the fulfilment of the function fit.

If the edges are tangent then if you have the "All tangentially connected edges" (expand the >> for that option in the chamfer dialog) selected and the shape applies then it will select the loop

GD&T A means of dimensioning and tolerancing a part with respect to relationship and function of that part. GD&T is used to define how a part feature relates the other part features in the same part or in a mating part; it’s a way to dimension and tolerance with respect to part’s function, the way it works.

Clearance: The difference between the size of the hole and the size of the shaft when the diameter of the shaft is smaller than the diameter of the hole.

Interference: The difference before mating between the size of the hole and the size of the shaft when the diameter of the shaft is larger than the diameter of the hole.

The tolerances defined in ISO 286-1 are applicable to size range from 0 mm to 3150 mm but there are exceptional cases defined in the standard which depends on tolerance selection. If the calculation results given by the tolerance calculator are "---", then this means the input parameters are not applicable according to ISO standard.

Designation of the tolerance class: The tolerance class shall be designated by the combination of an upper-case letter(s) for holes and lowercase letters for shafts identifying the fundamental deviation and by the number representing the standard tolerance grade. For example H7 tolerance class for holes and h7 tolerance class for shafts.

Lower deviation: The difference between the minimum limiting size and the corresponding nominal size of a feature.