Files with the extensions .bin and .hqx are encoded in MacBinary II/III and BinHex 4.0, respectively, and must be decoded before you can work with them (later versions of Classic Stuffit Expander (such as 5.5, included with Mac OS 8.x and 9) can do that, but evidently, the early version you're using can't, so you must either a) find a separate program to do it or b ) you can decode them on modern macOS, which shouldn't wreck the resource forks because as far as I know, they're still supported. .sea is a self extracting sit archive, most likely requiring System 7 to run (it can be extracted by Expander like a normal .sit file, but probably not by the old version.
The safest way would probably be a), but then there's the classic catch22, wherein you download the decoder, and you need it to decode itself, but you can't because you need to decode it first :sadmac:
Anyway, here's a program for decoding MacBinaryII (unfortunately requires System 7):
http://macintoshgarden.org/apps/macbinary-ii
And for BinHex 4.0 (this one appears to be System 6 compatible):
https://macintoshgarden.org/apps/binhex-40
I think the easiest way to solve that is to boot up mini vMac with System 7, MacBinary, BinHex (plus something to decode them), and/or a recent copy of Expander (5.5 is compatible with 7, I think), do all your decoding and expanding there, and then copy the results over via Floppy Emu to either the SE or the Classic.
I hope this helps!
c