The training sequence sounds like 56k to me ;)

Yes, it did. Did you forget that there were two different 56k standards and those did sound different when negotiating. 56k Flex versus v.90. Negotiation sounded really different depending from standard.

And how many people would have had a color monitor back then?

Many people had color monitors in the 1980s. For values of "monitors" that include television sets. The Commodore 64 and Vic 20 were color, as was the Tandy CoCo. Lots of others as well.

I opted for a hercules monochrome that was higher resolution than the color alternatives.

For PC connecting to monitor, CGA was introduced in 1981. I'd say by 1985, it was a very popular choice. Before that, many home computers that connected to television were already color.

EGA was introduced in 1984 too.

The Apple II was colour, and that thing came out in the late 70s.

For home machines most of them would have been colour by 1982-3. My first paid for job was Turbo Pascal on a CGA PC in 1984 so it was pretty wide spread.

I had an Apple ][ GS back then. Actually, I still have an 8088 with a color monitor and such, but I haven't got it set up, so I'm not even sure if it still works.

I had (still have, actually) an Amdek Color-I Plus on my Apple //e. It was relatively common at the time.