Clear explanation of international travel fees on Sect plan

Within one of the 215 countries included in the Select plan, what specific phone activities will incur costs above my basic monthly fee for my plan?  Again, assume I am i  one of the covered countries, e.g., Portugal. 

--I can receive calls from anywhere over the roaming international network for free?

--I can make calls to anywhere while on international roaming for free?

--I can use up to xx GB data per month for free?

-- I can send sms and mms messages for free?

-- I can receive sms and mms message for free?

-- My smartwatch, which is not on any plan- that is it is ONLY bluetoothed to my phone, can receive my phone's Bluetooth transmitted texts and notifications for free? ( it would cost if my watch were on a data plan?)

So there is no need to worry about surprise expenses, I simply activate international roaming before leaving the country?

Thank you in advance for clarifying clearly. I have read the rate chart and believe the above to be true.