Is it possible to finish all the henchmen quests in each chapter and how long do you have to wait between conversations until they'll talk about it again.

Yes, it's possible to finish all quests in every chapter.

The henchmens quest dialogues are not time-based, they're level-based; if they won't continue their story, try again when you've leveled up.

In theory, you can take one henchman through a chapter, finish their quest, then dump them near the end to pick up every other one and run through their quests within five minutes... provided you had the foresight to collect whatever strange items you came across.

I never tried this myself, but have read that you can select a henchman to join, run through the conversation available to that point, then dismiss them, pick up another henchman, and keep repeating until you talk to them all. Take whichever you want with you until you level up, then go back and do it all again. Should get you quite a few nice items in the end.

In Chapter 1 I had only done Tomi's quest by the time I had all the things for the cure. I went to the Trade of Blades and one-by-one talked to each individual over and over to get there quests. Whenever they would tell me that they would tell me the rest later I would hit "End Dialouge" and then immediately start a new conversation with the same person and they would continue the story. It turns out I had been fairly thorough in my looting and had all the items already. You get some good items and it really only takes you 10 minutes.