Amy did a great job answering your questions. Like she said the workbook pages are in the student book, not the teacher's guide. The sample book list will give you lots of ideas to choose from so it is well worthwhile. You could still choose your own books, but I like that I know if it is in the sample book list, it will be an ok choice for my dc to read without me pre-reading it. Carrie has done all the work for me there.

The book list also is going to show you the level and genre as well taking that work out of the picture too. Once you've chosen a book, you will just divide the number of pages by 15 days and see how that works out. If that seems like it will be way too few of pages each day for your dc then you might want to use that book for 10 days and pick another shorter book for 5 days. This is just my OCD nature, but I like to have things divide out nicely into chapters so I typically try to find a book whose chapters work out to be about the right length and number for 15 days or choose a book or two that works out that way. I hate stopping in the middle of a chapter but if it is a book with long chapters, then I try to find more natural divisions when dividing the reading. We have had a few books that were that way, but I try hard to avoid them.

I hope I didn't make that sound complicated, it isn't at all.
As far as writing, there will be some writing in the workbook, but not long essays or anything like that. DITHR definitely can be your only reading program, but if you are looking for a writing program also, you'll probably want to add something else. Carrie recommends for those not using the other HOD guides and just DITHR to use Igniting Your Writing. Here is a link to the language arts recommendations to go with DITHR:
http://www.heartofdakota.com/drawn-into ... ations.php
In case you hadn't seen it yet, here is a link to some of the sample pages for DITHR as well:
Teacher's guide intro:
http://www.heartofdakota.com/pdf/drawn- ... -intro.pdf
Teacher's guide first week:
http://www.heartofdakota.com/pdf/d1.pdf
Student book 2/3:
http://www.heartofdakota.com/pdf/d2.pdf
Student book 4/5:
http://www.heartofdakota.com/pdf/d3.pdf
Student book 6/7/8:
http://www.heartofdakota.com/pdf/student-6-7-8.pdf
If you have questions about what you'll need for each level, click on the light bulb on this page:
http://www.heartofdakota.com/drawn-into-packages.php and it will show what you need for the program.
