a few comments (still in Lesson One)

It gets easier.

I'd gotten out of the habit of a daily practice for quite some time, so while the material and practice are not new to me, I still experience my body and mental processes enduring some training.

The first session was the most challenging, and there was plenty enough of wanting the session to reach a timely end. This is very normal, and shouldn't discourage one from continuing the practice. Over even the first few sessions, concentration deepens and the practice becomes more natural.

Behaving in a manner that supports meditation:

Starting with the first instructional CD, one is introduced to a few behavioral suggestions intended to help with the practice. They are simple guidelines such as avoiding saying harmful things that may lead to troubled thoughts and difficulty concentrating during practice.

If you completely disregard these, I believe it's safe to say that your practice will be more difficult. If you have gotten yourself into trouble during the course of your daily life, that troubled mind will still be with you as you engage in your practice session. It's not that practice will be impossible, but the frustrations you've introduced can make it hard to relax and focus on the task at hand.

Workbook exercises:

Due to time constraints, I had been practicing the guided meditations for a few days before I made it to the exercises at the end of Lesson One in the workbook.

My impression now is that someone completely new to Insight Meditation practice may benefit from not only listening to the audio instruction for Lesson One (a few times, I'd suggest) but also read through the workbook introduction and Lesson One through the exercises before starting the guided meditations.

This might also be of value to someone looking to race through the coursework as quickly as possible for whatever reasons. (And I can think of a few perfectly good reasons one might wish to do so off-hand.)

The reason for this is that the exercises may be performed during the guided meditation sessions. The guided meditations aren't of the "Now imagine you're walking along a solitary beach..." variety, but simply a dharma teacher gently coaching you through a practice session just as would happen on retreat.