The endorsement thing would be a neat feature to see available in the API! We're actually planning to sit down in the November/December timeframe and try to evaluate how best we can take advantage of more features of the API than we do right now. Right now, it's very focused on login/registration and profile import. That's how JFBConnect was for it's first year of life as that's a strong foundation to build on, but now we need to start expanding into other things.. so we love the feedback!
As for skills, we'll have to look into it. Just to check, are you using a 'new' LinkedIn app that requests permissions from the user or an older one (created before August this year) that doesn't? The old apps should be upgraded very soon as well, but for now, knowing what app type you have may help us understand the issue better.