a) Rabbi Mayer Birnbaum, Shlita, writes (in Shamor L’Kad’sho: Practical Halachos of Shabbos, p.17), "If siddurim were piled up after a minyan, you may not sort out the Ashkenaz and Sefard siddurim in order to put them away [however, if you read a little from each siddur, you may put each one into its proper place after reading from it] (Hilchos Shabbos by Rav Shimon Eider, Shlita, p.184 and Igros Moshe, Orach Chaim 4:74 Borer #12)." Of course, Borer on seforim applies to other mixtures of seforim as well. There may be cases where you may be lenient in this area based on facts and circumstances. Please consult your Rav with specific shailos.

b) In many city homes, the front door leads directly to front steps which lead to a short path leading to the sidewalk. We have noticed many unknowing individuals on Shabbos holding a child, looking into a Sefer, or even taking out a chair to sit on the front steps outside. We caution that without an eruv around the house, the front steps may not be considered part of your home, and it may not be permissible to carry there. The fact that the steps are attached to, or project from, the house by itself is insufficient. We urge you to consult with your Rav as to the principles of Gud Achis, Mechitzos and Reshus HaYachid prior to carrying on your front steps on Shabbos.