In general, if you want to acquire multiple channels where every channel has different parameters, you have to call CreateVoltageChannel multiple times, for every channel with different parameters. You can only group these channels together that have the same parameters (for example the same Range).
It is no problem to define a task with multiple channels, where every channel has different ranges, but it is not possible to define differnt sampling rates for these channels. Do use different sampling rates, you have to use different tasks. Take care that not all boards support different samplingrates at the same time. For example E-Series or M-Series boards do not support to acuire channels with different sampling rates at the same time.