1. Yes, these can be applied together. The 11th harmonic will be of the multiplied frequency. So if the current frequency is 5, and you chose a Frequency Multiplier of 10, then (5 * 10 * 11 = 550) Hz will be modulated by or added to (5 * 10 = 50).
2. Yes you can use both together and your reasoning is correct.
You have two ways to apply the 11th harmonic.
You can use F2 = F1 x 11 which will create a second simultaneous frequency on Out1 or,
you can use Out2 = Out1 x 11 which will create the 11th harmonic on Out2.
So if you had 10Hz in the frequency list; and a multiplier of 1000, your Out1 would be 10,000Hz
The Holland output frequency would then be 10,000 x 11 = 110,000 Hz
Spooky has a lot of knobs and settings which you can change.
Another way to set a higher frequency is to use the minimum/maximum frequency setting instead of the multiplier - the choice is up to you.
For more details, please check the link: