Can people who have used/were around at this time (early 1970s) give a description of the typical dev environment?

Also helpful: C history https://en.wikipedia.org/wiki/C_language#History

From wikipedia, early Unix was developed on PDP/11 (16-bit).

signed 16-bit ints, 8-bit chars, arrays of those previous types.

identifiers were limited in length? (I'm seeing 8 chars, lowercase, as the longest)

octal numeric constants, was hexadecimal used?

there was only a line editor available (vi was 1976)

did the file system support directories at that point?

no C preprocessor, no header files. (1973)

no make/makefiles (1976)

was there a std library used with the linker or an archive of object files that was the 'standard' library?

Bourne shell wasn't around (1979), so wikipedia seems to point to the Thompson shell - https://en.wikipedia.org/wiki/Thompson_shell

was there a debugger or was printf the only tool?