I'm still using LR4.4, but the learning process would be similar. I purchased "The Adobe Photoshop Lightroom 4 Book for Digital Photographers" by Scott Kelby and read the first three or four chapters before digging into the program. there are some key decisions you need to make concerning location of files and some set-up parameters that are best done before you do much with the program.
I only have experience with Kelby Training LR books and videos and i recommend those highly. Kelby has a number of LR5 training materials available. If you don't want to spend any money on training materials, Adobe offers some very god free videos and YouTube has lots of free options.
I think you will love LightRoom once you get comfortable with it - I do.
Yes, the adobe video's are excellent and you have to dig around the sight a little bit to find them or check them out on youtube. They are really great and can help you in the filing decisions as well. I think Julianne Kost does a lot of them for Adobe, I believe she is an Adobe Evangelist. She's quite good to help learn the system...
5D Mark III, 100-400L, 70-200 2.8L II, 24-105L, 16-35L IS, 17-40L, 85mm 1.8, Samy 14mm 2.8, 600 EX-RT, 580EX II, 430EX II, 1.4X III, 2.0X III