How to use Google Analytics+ for subsites

Several questions:
1. Does this plugin replace the Multisite Analytics plugin?
2. If the client wants to use Google Analytics dashboard, will the information show up there? Will it be separated out by site? or will each site need its own Analytics account for that to work. These sites are all part of one company and I think they'd prefer the information all in one place, but if it would be difficult to separate, then it would be better to set them up with separate accounts.
3. The sites are subdirectories - I gather that's supported?