A lot of those shows are great, but that is all I've been saying, it doesn't always have to be realistic to enjoy. Yeah maybe sound and an up/down orientation isn't remotely realistic, but if your like me and enjoyed the epic space combat in movies like Star Wars or the first two Stargate series, it simply did not matter.
What matters is if your enjoying something or not.
Now if you want your galactic age to be realistic, that is fine, but I would recommend not going strictly realistic in your approach.
Maybe an alien empire with a race that is humanoid does exist, or more than one. Maybe in your fictional future there is a good reason for that. Perhaps in the distant, distant past a super-trans-galactic civilization existed and modified life on many worlds to suit their purposes.
An example of something like this is the Xel-Naga of the Starcraft game setting, the Celestials of Marvel Comics and the list goes on. The game galactic civilizations main plot was based on an ancient war between the beneviolent progenitors and another power race known as the Dread Lords. These races shaped how the later civilizations of the galaxy developed, and why Humans and Altaireans(I think that is how it is spelled) resembled each other.
The future of your mod is yours to create, I believe you both can create a good one, realistic or not.