Gateway Downlink Frequencies for Class C Devices

Countries Frequency Plan
1

the question is not specifically the implementation of TTN community network on but on lorawan specs in general.

I intend to build a network with one or more gateways in a private lorawan network. all devices are class C devices. is it possible for different devices to listen to different RX2 frequencies class C operation? and of course, the gateway will use different downlink frequencies for different devices (to reiterate, this is not for class A operation).

the intention is to maximize all available channels while maintaining duty cycle per channel.

2

That depends on the backend software you will be using. Keep in mind TTN uses an RX2 frequency (in EU) in the 10% band and all other frequencies are in 1%, so switching frequencies might reduce in stead of increase available airtime.
AFAIK TTN V3 does not support this.