Were there any other historical versions?
Yes, there were, but the history of AMIS is just a little too old to be extensively archived.
The initial proposal dates back to September 1991 in release 27 of the Interrupt List; this is mentioned in the announcement of version 2 of the proposal:
In the September 1 release of the interrupt list (INTER27), I made a proposal
for an alternate multiplex interrupt with a standardized method for sharing
multiplex numbers and a set of standard function calls. After some
discussions and useful suggestions, I now have the following revised
Version 2 suggested using interrupt 0x7D.
Walnut Creek’s May 1992 Garbo archive CD-ROM contains release 29 of the Interrupt List, which documents AMIS version 3.2.1. This already has two known signatures for software not written by Ralf Brown.
Walnut Creek’s June 1992 Simtel-20 MS-DOS archive CD-ROM contains AMISLIB 0.83, based on version 3.4 of the spec; however the library doesn’t include the spec itself. This contains a changelog covering version 0.80, 0.81, 0.82 and 0.83 of the library, suggesting that at least those were distributed. The same CD-ROM contains release 30 of the Interrupt List, which documents AMIS version 3.4.
I get the impression from the announcement of AMISLIB version 0.81 that the first publicly-available version of AMISLIB was 0.80:
I have just released an update (v0.81) to yesterday's preliminary
version of AMISLIB, a library for implementing TSRs which comply with
the Alternate Multiplex Interrupt Spec I've been propounding for the
past several months.
Other archive CD-ROMs likely contain other releases of at least the Interrupt List, with different versions of the spec, although since version 3.4 was released by June 1992, finding older versions is likely to be difficult (Walnut Creek at least only started in 1991, and I don’t know how many DOS-related archive CD-ROMs they published before mid-1992).
And is there any material on the known versions that I did not list here?
AMISLIB 0.92 itself contains version 3.5.1 of the spec; the differences with version 3.5 are that bit 6 of byte 0 in the hotkey list is used, and the list of known signatures is significantly expanded.