Steel was introduced in the past though...since we saw him emerge at the same time as Superman did. We just don't know when "Death of Superman" happened or how it happened this time around. As someone else suggested earlier in the thread they most likely happened differently in the 52 'Verse than in the DCU. Regarding Superboy, I'm still waiting to touch back on to Lois's investigation into NoWhere.
House of UIster...did a little digging around, and from the reviews that I've read on eight, no one knows who the "little satan" is that Glenmorgan was talking about or who we saw making those deals earlier in the book. He is obviously some kind of time traveller who has become an information and power broker in the "present" time. It's entirely possible he is a new character Morrison created. I can't think of who he might be at all. Perhaps an evil Mxy (not Mxy, but an evil Fifth Dimension being).