Can I access to many Youtube channels reports with a only one account?

Question 1

Yes, you actually can have these different channels linked under a single Google account.

1) Set up a Google Plus Page for your YouTube account via https://www.youtube.com/account (requires g+ account) Note: This may overwrite avatar and channel title, and may change your YouTube display name to whatever you set your Page Title to be.

2) Your personal g+ account will be the owner of this Google plus page.

3) Repeat for other accounts, setting up their own google plus pages.

4) You can add your main personal g+ account (if you have one for each unique gmail) as a "manager" of these other pages, giving a single login access to the pages (and therefore all the associated YouTube accounts) via the drop down "switch acocunts" on YouTube (top right drop down)

5) After a page is old enough (2 weeks?) you can change owners so your main g+ page owns the page. Not necessary but helps consolidate + lets you abandon other personal g+ accounts.

Let me know if you're able to follow that. There are benefits to doing this with only a single channel. You won't be able to see "combined" analytics but you can switch accounts much, much easier.

Question 2

This link provides the youtube channel report in range. But when used with google php library it get hooked in a "User login required Error!"

https://developers.google.com/apis-explorer/#p/youtubeAnalytics/v1/youtubeAnalytics.reports.query?ids=channel%253D%253DMINE&start-date=2014-05-01&end-date=2014-06-30&metrics=views&dimensions=day&_h=3&

Is there any way i can access the channel analytics report in youtube V3 same as like in v3

http://developers.google.com/apis-explorer/#p/youtube/v3/youtube.channels.list?part=statistics&id=UCMGgBRBiijmpgL3xNuiDVOQ&_h=10&