Is one required to take 3 steps forward after finishing Shmona Esrei/Ammida of Arvit after he has taken the 3 steps backwards?
There is no requirement to take three steps forward at the end of any shmoneh esrei prayer, whether that be shacharit, mincha, or ma'ariv. There is a halacha that one should take three steps forward for the beginning of kedusha. Of course, this is not applicable to ma'ariv.
Rav Shlomo Zalman Auerbach is quoted in Halichos Shlomo (Hilchos Teffilah chapter 13- siman 12) saying that one who finishes his Shmona Esrei and has taken his three steps back should stand in place and not move his feet until the Shaliach Tzibbur had begun Kaddish. In the explanation below (#19) he explains that the reason for this is different than other teffilos for there is no Chazaras Hashat"z, nevertheless since the Shaliach Tzibbur is saying Tiskabel, which is an aspect of teffilah one should wait for the Kaddish to begin.
-Clearly, from this explanation we see that despite the fact that one is waiting in his place after the Shmona Esrei, similar to what we do for shacharis and mincha, nevertheless returning forward with three steps is not necessary, for the three steps are in order to return to your place for the repetition of the Chazaras Hashat"z.