Go through the program after 1 year and then reevaluate. Don't worry about that now!
Doing four sessions is fine as long as she loves it and you do not feel that she is going to lose interest and burn out. You know your child better than any of us, so you make the call. What worked well with my kids is I printed off 2 categories every week and slipped them into the presentation binders
http://forum.brillkids.com/announcements/introducing-the-brillkids-presentation-binder-set!/ We did these randomly throughout the week and replaced them on Sundays, usually she mastered them over the course of the week. Then, I continued to show the daily on the computer as designed and didn't worry too much about retention, only exposure. You can do the same "on screen" but we liked the variety of some learning on screen, and some learning using the binders.
Another thing I used to do with my kids is sing the ABC song at every diaper change. If I had to do it again, I would sing it phonetically first to the regular tune of the ABC's. Aah, Buh, Cuh, Duh, etc. Now, that was a poor visual representation which is not as "clean" as you should make it sound, try to avoid adding random vowel sounds to the consonant.
And whether you choose to print flash cards or use LR files, the information is the same but with a print out you lose the audio (for example, the real animal sounds which my kids LOVED!) and the variety of color/font of the text and the mixed up order. Even so, we liked to do both for variety. The downside is that you go through a lot of ink! Follow your child and she'll tell you what she prefers.