I would really doubt you'll get your lilacs to bloom indoors with only 4hr. of sun through a window. The same with your bearded iris. They need a lot more sun than that. In too much shade, tall bearded iris grow tall and just flop over. They will not be a nice indoor plant.
What about trying Cannas instead of the iris? They are gorgeous, come in lots of colors, shapes and sizes including wonderful variegated leaf colors, and they will keep blooming for months, not have one big show for a couple of weeks like the iris do. Much better value for your effort in my opinion, and they are more likely to bloom with less sun, too. If your windows have sun through the winter, they will bloom year 'round for you.
