These passwords are just meant to help those out the most, so I don't see the point in making passwords without E-Tanks at all. The more the better.
And I put these up in the order they go as I suggested in the walkthrough. Each person is more than welcome to post his/her own, but this is as far as I'm going.
No no. What I mean is when you use 4-tank new game password to start your loop. If you start with Chun-Li, you will end up with the same 4-tanks password with 1 less collectable E-tank. And that's just a waste of opportunity.
If you start the loop from Blanka stage, then People could have use a password where you beat Blanka, Rose, Rolanto, and Urien with 4 E-tanks. And the one who use that password will be able to collect the other 4 E-tanks from the rest of the stages.
As of why there isn't any password that allows you to have more than 4 E-tanks is basically what n00bsaib0t said. Since they share the same Password method, it is impossible to have more than 4 tanks. (You will understand it once you know how the password works....And believe me, there is no way to make it so that we can have more than 4 E-tanks password.)