It’s helpful to distinguish form and function in these cases. Perhaps in an attempt to do so, grammarians, in describing the former, seem increasingly to refer to ‘the –ing form of the verb’, rather than using terms like gerund or verbal noun. No one can dispute that that is what it is, and it leaves the way clear for an examination of the function.
This form of the verb can perform verbal, nominal and adjectival functions. In your first example, cooking is, as you say, a noun, functioning as the subject of is. In the second, it’s an adjective, modifying apples.
If we speak or hear of a cleaning lady, we know that cleaning is an adjective because, if for no other reason, cleaning and lady quite often collocate in this way. It is hard to think of circumstances in which we would want to use a cleaning lady to describe a woman who was actually engaged in household cleansing duties at the time of speaking. In other words, a cleaning lady is a lady who cleans, and not a lady who is cleaning.
In your other examples, the -ing forms are also adjectives. They are, however, a little different, in that we can’t say that they describe an X that does something rather than an X that is doing something. They do neither. A talking point doesn’t talk, reading material don’t read, a cutting board doesn’t cut and a watering can doesn’t . . . Ah. Well, yes, a watering can does water, but the point is that it doesn’t water of its own accord. It’s a can for watering, just as a cutting board is a board for cutting.
In these cases, ambiguity is unlikely. The ‘Longman Student Grammar of Spoken and Written English’ points out that ambiguity with the use of ‘-ing’ form can nevertheless arise when it follows a main verb (Is it a noun or a verb?), when it modifies a following noun (Is it a noun or an adjective?) and where it follows the verb be without other modifiers (Is it a verb or an adjective?).