As of now, Server 3 is open for new registrations.
There are no changes compared to S2 in troops or buildings stats or costs.

Server 3 will be launched on January 19th, at 13:00 server time (11:00 AM GMT). As of now registrations on S2 are closed.
If there are any bloggers playing the game, we’re offering 3 months of free VIP for anyone that announces the start of Server 3 on their blog. I’m talking about established blogs (at [...]

As the title says, the Gunpowder Age has been launched on S2.
You can upgrade to the second age from the Gunpowder Age tab in the City Hall.
Requirements:

City Hall lvl 20
at least 2 villages
at least 600 population
30,000 for each resource
plus 10% of the training costs of all the military units you currently own

Training prices and training [...]