How do I suspend my plan while keeping my number?

Hi. I will be leaving the US for around 6 months, and during that time I would like to suspend my phone plan. Currently, my phone plan is prepaid ($40 Simply Prepaid 10GB LTE – Unlimited Talk, Text, Data). I know that I can suspend my account twice a year for a maximum period of 90 days for each suspension and that I will be charged $10 per billing cycle. I still have questions though.

1. what does it mean "billing period"? Is it $10 per month? Or does that mean $10 per suspension period (so around $3.33/moth)?

2. how do I actually suspend it? The instruction on the website says,

1. Visita Mi T-Mobile e ingresa a tu cuenta.
2. Haz clic  MÓVIL.
3. Haz clic en Informar como perdido o robado o Suspensión temporal, según el tipo de suspensión que necesites.
4. Sigue los pasos en pantalla para suspender o restaurar tu línea de servicio.

However, when I clicked the Mi T-Mobile​link, I couldn't see MÓVIL.

Here is why I see:

and when I clicked "Edit plan," I see this:

The instruction is a bit confusing. Not sure if it has anything to do with my "Prepaid" method??

What IF I just stop refilling $40 a month during that 6 months period? Can I still keep my phone number back after 6 months when I get back to the US??

¡Gracias!