I can't answer all your questions, but will attempt some. I have no idea how flexible Worldmark is so it's hard to compare.
With CI there is no home resort. You can use your points at any of the CI locations. Minimum stay is 2 nights or 3 nights for long weekends (except within 14 days there's no minimum). You can book 11 months in advance for 6 or more nights, and 6 months in advance for less than 6 nights.
The peak time question is hard to answer without knowing where you'd like to go. The ski resorts, especially Whister and Tremblant are booked for Xmas, New Year's and President's week and much of the winter school holiday weeks 11 months in advance, and many owners have enough points to reserve much more than 6 nights.
Summer is generally relatively easy to book, though there are certain events that people go to and book early. As an example, I just booked 6 nights at Tremblant for their blues festival for next July, and did not get the type of unit I really wanted because this year I was able to get 5 nights there much closer to the date (probably a cancellation). I do all my reservations online, and it's a very easy to use system.
You can cancel up to 30 days of your check-in date and get the points back. There is a $25 fee, unless you do it on the phone and get another reservation that uses more points.
An owner can transfer points to someone else for use - there is a form to complete, but whether one pays for them is probably up to the two parties (I've never done this). You can also borrow your own points from the next use year.