1: Download music from iCloud to your machine, you can upload it to play music. Get your iTunes data and when you bought HTC One simply copy and paste it into your new phones' memory like pen drive.
2: Yes, Google play has its own services for streaming music, moves and all.
Its not like you will be in a mess while switching, once you are done transferring you won't feel any problem. But finding your data where iTunes stores on your machine is bit of mess.