Roman Coins

I have these 3 coins that I bought from a vendor about 2-3 years ago. He said that they are all veritable Roman coins. The last one I don't think can ever be identified but the first two might have a chance. I could distinguish on the first coin coin the letters "niano" or "aiano" coming from Traiano probably but the coins I've seen online mostly have the name of the Emperor on the obverse rather than on the reverse. Can anyone help me with some more details.

On the obverse of coin #1:

D N VALE... = D(ominus) N(oster) Valen...

It could be Valentinian I (364-375), Valens (364-378) or less likely Valentinian II (375-392 I think). To me it looks like Valens.

Search the Wildwinds site for Valentinian I and Valens, keeping in mind your reverse, which should be easy enough to recognize once you spot it. Pay attention to metal, weight and diameter.

Valens: http://www.wildwinds.com/coins/ric/valens/t.html

Valentinian I: http://www.wildwinds.com/coins/ric/valentinian_I/t.html

(Copy & paste the links in a new window if they don't work, as this happens occasionally with the Wildwinds site.)

I've identified the first coin more or less, thanks to your help Camerinvs. I didn't realize that there is a D N in the beginning. The coin was minted in Heraclea (on the coast of Turkey) at around 370 AD (tesorillo.com helped me here, they have all the mints categorized by the symbols that appear on the respective coins). I cannot tell for sure though whether it is Valens or Valentinian I, but I tend to believe it is Valens because of the mint that was located close to Constantinople.

I'm thinking about the second coin that it might be Artemis holding a torch/spear. I found these two coins:
http://www.asiaminorcoins.com/gallery/displayimage.php?album=search&cat=0&pid=10899
and
http://www.wildwinds.com/coins/ric/marcus_aurelius/_amphipolis_AE18_Moushmov_6085.jpg
I'm waiting for some opinions.