OK, I've reproduced the problem, and here's what I'd do.
You've placed RGB images over CMYK vector paterns made in Illustrator, which in some ways makes things more complex than if the imges and backgrounds were all in a single color space, but it looks as if only the backgrounds are going to be affected by any flattening that will be taking place in the conversion, so if there is any color shifting due to the flattening and choice of space, and I don't see any, it will be isolated to the background texture and probably not noticeable.
Since you have two destinations, you need two differnt PDFs. The sample is very interesting, but I suspect the print run will be small -- limited to family members -- so the first thing to do is ask the printer what PDF export settings he wants you to use. If you're going to have this printed somewhere like Kinkos or Staples, they probably can't answer that question, and I'd stick with the High Quality Print preset, and be sure the compatibility is set to Acrobat 5 or higher so the transparency isn't flattened. Print one page as a sample before committing to the entire job to check the color (and don't expect miracles from the average copy shop running a color copier -- they usually just aren't set up to handle color management and matching).
For the screen version, set the blend space to RGB and choose the Smallest File Size preset. you shouldn't get the warning (but you could ignore it even if you did). If the file is still too big, set the compressin settings to downsample color and grayscale to 75 ppi and lineart to 600 and see if that helps before you try reducing the quality in the compression. The prints off a desktop printer won't be quite as good as they will be at 100ppi, but probably acceptable on most inexpensive paper stocks that peopl seem to use, and hopefully they are going to get the better printed version, anyway.
Peter