What Are My Choices For Data Coverage On T-Mobile For Business Data Lines?

I have a business account with two data lines.

One is Bus Unl Tablet 10 GB HS TI and the other is 5G Bus Mobile Int 30GB

I will be traveling to Belize, Honduras and Mexico soon. 

What data coverage will I have with these and at what speeds?

If I want to add additional coverage, what would the cost be and speed?

Would it matter which line I add it to?