Hi there mouton73!
I have a couple of articles that can address your questions and help resolve any issues you may be seeing. First, I would recommend reinstalling iTunes on your PC:
That article can help walk you through the reinstallation step-by-step. If you are still experiencing issues after following the steps to reinstall your operating system, then you may need to re-create your iTunes library by following these steps:
As for the download times, we also have an article that addresses that concern:
Thanks for using the Apple Support Communities!