There seems to be a "Jhana factor" in the background of every phase.
AP=Jhana 1, DN=Jhana 2-3, EQ=Jhana 4.
Yes, the vipassana jhanas and samatha jhanas are closely related. EQ and jhana 4 occur in the same stratum of mind, using KF's terminology. You can actually slide back and forth between concentration and insight stages with some practice, it's a matter of how much you allow the 3C's to show themselves, if that makes sense. Jhana 1 is actually associated with the pre-vipassana stages due to the whole sustained effort aspect, AP is jhana 2, DN is jhana 3, etc...
About progress, I don't have the options of retreats. I have a job, a wife and pets. I have a stiff spine (hours of working with a PC in a bad posture).
So, my progress won't be as "fast" as others.
I don't have the option of retreats either. I have three kids, one on the way, a wife, and a full-time job. The good news is, I made it all the way to EQ in these circumstances, and I actually didn't even know what the Progress of Insight was. It only took me a couple of months from A&P to EQ. How many hours a day do you watch TV? Are you mindful at work? Do you note throughout the day? Do you practice any kind of sleep or dream yoga or do you just hit the sack and conk out? All these are important considerations. Enlightenment for householders is very possible, check out the book on Dipa Ma for some inspiration.
Some people spend years on retreat and yet fail utterly at insight practice.
I'm not so sure about the lessons thing. If each stage carried lessons, you should stop cycling after SE (all lessons learned).
I can't speak for Daniel, but I think what he meant was, insight has to mature before you can move on to the next insight stage. That's the way it is referred to in more traditional texts, insight maturing. It's difficult to describe how this happens. You just have to "get it." The best way to do this is practice, practice, practice, and a sense of surrendering to the process.\
Cycling is related to the way the mind relates to phenomena, not necessarily to whether you have learned every lesson of the stages.