How do I stimulate a neuron extracellularly, specifically the sphenopalatine ganglion

Apologies if this is too basic of a question, but I am an electrical engineer, just getting into neuromodulation/neurostimulation.

For my senior project, I am trying to make a device that stimulates the sphenopalatine ganglion. I have read as much as I can online, but some basic questions seem to not be answered. Answers to any of these would be really really helpful, as well as any resources to continue my research:

1. When I’m trying to ‘stimulate’ a neuron, I am really trying to trigger an action potential, correct?
2. Can I just send current across the exterior of the membrane to trigger an action potential?
3. Is is possible to stimulate a neuron without piercing the membrane? I know an action potential is the voltage across the membrane, so how can I change that voltage without piercing the membrane?
4. I believe I need to record the action potentials of the neuron, to make sure that my device is targeting the correct location and working properly, is this possible without piercing the neuron?
5. From the literature, I found that a 10 Hz electrical pulse works best for the sphenopalatine ganglion stimulation, but I am not sure how frequency plays a role in this.

Sorry again if that is a lot, but I am new to the field and have a lot of questions. Thanks in advance for any help!