I'm hoping for an Alchemist/Gunslinger combo. It just seems like guns would the type of thing for an alchemist to use and it would be nice if there was some version proficient with them. I also second the call for a Monk/Fighter. A tougher, full BAB Monk with a few less mystical qualities would be awesome. I would miss some of the mystical stuff but most of it is useless or very situational.
My reading of that, as well as everyone else I know, is that the first five levels are 1, the second five are 2, etc. This has been the interpretation used by everyone on these boards that I've seen and Jason hasn't ever corrected us.
I wouldn't be too disappointed if that is the case since I am creating a Summoner for a new campaign soon, but it just seems like the Summoner would have to possess five levels before getting the evolution. I'm not saying I'm right but I don't think a clarification in the text could hurt.