If my opponent plays an Exalted Angel face down as a morph creature, and I cast Mana Drain targetting the Morph, how much mana will I get next main phase?

Is the Morph's mana cost 3 because of the morph ability?  Or is it 6 because the card is acutally Exalted Angel, similar to how you get 5 mana for mana draining a misdirection even though they played misdirection without paying it's mana cost?  Or is it zero because morph is strange?

Thanks.

Hi.

I have out 25 1/1 Myr Tokens via Myr Incubator:

6, T, Sacrifice Myr Incubator: Search your library for any number of artifact cards, remove them from the game, then put that many 1/1 Myr artifact creature tokens into play. Then shuffle your library.

My opponent casts Echoing Truth targetting one of my Myr Tokens:

Return target nonland permanent and all other permanents with the same name as that permanent to their owners' hands.

Now I believe that I would only lose the one token targetted, as the Myr Tokens are 1/1 Artifact creatures with the creature type - Myr, and have no name, therefore only the second ability of Echoing Truth won't be an issue.

My opponent says that the Myr tokens all share the same name and therefore will all be bounced.

What really happens here?

So.. my question is this:

If you have a card that says to look for a land in your library and 'put that land into play' [like Reap and Sow] but the land you look for says 'comes into play tapped' [Shivan Oasis] would you still put the land into play?

What if the card says to put it into play untapped? [not sure if any do, but what if?]  Would the lands comes into play tapped line override that?

Thanks.