Welcome......
You will really fall in love with this country, driving from the south to the north you take aprox. 6-6.5 hours. And from there is what you like the most.
The south (algarve) is well known for the beaches and tourism, as you leave algarve you will enter in Alentejo ( between lisbon and Algarve) , that region is well known for the wines and some monuments like Evora , beja and Aviz , known for the Knights, great place to go.
In Lisbon , capital of the country , you will have a lots monuments , churches , gardens and museums. And beautifull for their natural light.When you start to drive north of Lisbon you have a place called Aveiro , knowed by the seafood , the river (ria de aveiro) and for their unique way to decorate the boats.
If you like snow , the Star mountain, is a good place to go between January and May.
And then you have the North of the country........that you can skip it!
Joking
I belive that my friends from the North will
at this time.
The North is wonderfull for the landscapes , lot's of green , great hospitality , people very friendly. So as you see you have pleanty of choice, is up to you.
About the ISV , you are true , it's
Just an example i was trying to buy a SAAB 900 turbo coupe, latest version from a friend of mine that was american. He would sold me the car for 1000 Euros and just to pass to Portuguese plates i had to pay ISV if the car was new.....around 8000 Euros. What you need let us know.
Best regards......