Lease time - 12months/6month

What's the standard lease time in Portugal? 12 months?

What's the rental law looks like? Is it same like in the US - lease cannot be broken - needs to be paid in full even if a tenant moves away (with exception of subletting)?

It is not like in US. I am from Washington DC, I am living in Lisbon. You can negotiate with a landlord the number of months, break the lease, price... You don't pay it in full - pay the rent monthly.