1.) No way around instaling apps and os again. Clone doesn't always work even with identical systems and new hardware can cause really strange windows behavior if it boots at all.
2.) The benefit is if the drive fails for some reason or another, any data on the other drive is still safe. Pictures, photos, work documents etc. I've moved away from a single point of failure and mirror all important data on my OS drive to second drive.
3.) Install steam, select games you want to reinstall and let it do its thing, go to work, come back home and start playing.