One relevant question is when on the path is jhana necessary. If jhana is needed even for stream-entry, your questions matter even more. However, I find arguments that jhana is not needed for stream-entry and likely not needed for once-return fairly persuasive. Stream-entry in the suttas almost invariably arises in a listener during or after a dhamma talk by the Buddha or one of his disciples (their mind needing, though, to be in a suitably receptive and ready state) and not by going off to do meditation. There is very little in the way of concrete association between the first two path stages in the suttas and jhana. However, there’s much to suggest that jhana is needed for non-return (and by implication arahantship). Bhikkhu Bodhi has a very nice article on all this: The Jhanas and the Lay Disciple According to the Pali Suttas.
On the other hand, the idea that jhana is needed for all path stages is fairly common, e.g. I’ve read arguments by Thanissaro Bhikkhu to this effect. The primary argument in this case is usually based on suttas in the Indriya Samyutta of the SN. There are suttas there ranking the various types of noble disciples (and faith- and Dhamma-followers too) according to their degree of establishment in the five faculties (including the faculty of samadhi), with increasing establishment correlating with increasing advancement on the path. All of these types of disciple are described as having some establishment in these faculties. The argument then goes that faculty of samadhi is jhana. There are certainly suttas that give the four jhana as the definition of samma samadhi. The Bhikkhu Bodhi article above does argue that this is probably too literal a reading.
Analayo’s Definitions of Right Concentration in Comparative Perspective (as just already linked to above by @Erika_ODonnell) above gives an IMO fairly convincing parallel-based argument against this line of reasoning. This fairly tight linkage between samma samadhi and jhana seems to be largely a Pali thing and hence quite possibly a somewhat later development. Taking the parallels into account, it seems there is likely room for non-jhana samma samadhi within the overall samma samadhi umbrella (maybe non-jhanic samma samadhi was more typical for the first two path stages).
My reading is it seems one can probably make quite a bit of progress without jhana: to stream-entry and substantial weakening of the fetters of sensual desire and ill-will. Maybe this progress in turn makes achieving jhana a lot easier. AN9.36 seems to indicate at least first jhana is necessary for non-return and complete elimination of the fetters of sensual desire and ill-will. Though there often seems to be a strong association with the mastery of all four jhanas and non-return. However, I guess with non-return, the hindrances and greed, hatred and delusion must have been weakened enough that mastery of the remaining jhana shouldn’t be at all hard (maybe explaining this close association).