1.A very muddled reference: The Prytaneion was, by all accounts, a completely different building from the Tholos (Thompson and Wycherley  46-47). According to the Suda's own reference to the Prytaneion, the Prytaneion was also called a "storehouse of fire", which may explain the baffling reference here to "storehouse of wheat", a function for which, as far as we know, the Tholos did not serve. The mistake may have arisen from a misreading of the Greek either by our author or his source (puro/s = "of fire", purw=n = "of wheat"). There also seems to be some folk-etymology being drawn between the words "prytaneis" and the word for wheat and/or fire, "pur-". This etymology has no basis in fact, though the actual etymology of "prytaneis" is unknown.
2. This last sentence is best explained as a second definition conflated from a different source. It does not refer to a different building.
Wycherley, R.E. (1957) The Athenian Agora III: Literary and Epigraphical Testimonia. Princeton.