She will be working the undercard, particularly the Senate very hard. Weird Harry has to be unseated as Senate Majority Leader.
As to Ryan being the future of the Republican Party... It remains to be seen how he handles the coming sh!t storm the Dems are going to throw at him. It is one thing to have the media write nasty things about you. It is quite another to have press pervs stalking your family. Plus if he isn't willing to press for a complete overhaul of the House and Senate Republican leadership, he will not last as the new face of the party.
That's the only thing anyone can say about Romney -- including Romney himself!
As to why Gingrich, Bachmann and Palin weren't invited to speak . . . long memories, maybe? I seem to recall reading that Reagan spoke at the '76 GOP convention and wowed them so much that there was much shaking of heads among the delegates and asking, "Why didn't we nominate him?"