Maximum electrical outlets in room

Yes, generally speaking you can have as many receptacles as you want on a circuit. There are limitations in some jurisdictions, but 12 - which is really 6 x duplex - is not very many and is unlikely to be a problem.

There are limitations on splitting circuits across multiple rooms, generally when kitchens or bathrooms are involved. But most other rooms have no restrictions.

A few things to keep in mind:

• Total power consumption. Obviously, you already have this under control. When it is practical (relatively easy to run another circuit, panel space available), running an additional circuit is often better, as it allows higher total power consumption. That is not an issue for most consumer electronics, but if you plan to add a laser printer or any other high power devices then an additional circuit may be helpful.
• Surge protection. I always recommend putting all high value electronics on a good quality surge protector. While there are 1 & 2 receptacle surge protectors available, most common are larger surge protectors - typically 5 to 8 receptacles. That can help a lot in terms of "where to plug everything in". That being said, more receptacles are still often better, particularly if they are spaced in more useful locations.