Oh my. You caught THEM ALL! I had wondered if the young Tsukihara-san clue was a bit too vague, but if you caught on then I guess it's not too far fetched. >.< Thanks for listing them out , it helps !
I've watched my fair share of the richxpoor dramas, so I guess I can confirm there was heavy influence from there haha.
(Yes, it is. The only reason old Tsukihara went the personal route was because he got news of what Izumi was doing over there ^^)