I am having trouble in accessing Yahoo Mail for iOS, thereby i also want to add Gmail Accounts Using Mail with other apps. can i do this in a very simple way?

Yes, you can do this, by doing some simple steps.

1) The first step, make sure you have a current yahoo account.

2) After this login into Gmail.

3) Then, go to settings and click on accounts and import tabs.

4) After that fill the required information like email, number

5) After doing all this, You will get a verification code.

and If your yahoo account is not working in your ios device it means, your account is not updated, for getting the solution of your yahoo account, you can connect with yahoo support team and with the help of yahoo experts you can update your yahoo account.  http://www.exactrelease.org/get-your-yahoo-messenger-updat-link-1082672.html