Hi Fil,
Portugal does have a modern telecom infrastructure because it has only recently been developed (recently by comparison to the US or Northern Europe).Yes fibre is in many places but notice that Portugal is a long thin country. Most people and therefore infrastructure is concentrated from the middle to the West - the ocean. To the East is much less developed and ADSL is still common outside the cities. The telecom companies are notorious for never committing in writing, pestering you constantly and being very difficult to leave. I don't think this is unique to Portugal as the trend is growing everywhere. That said I find the prices for telecoms is about the same as anywhere else in Europe.
There are many Km's of toll roads, they are very nice roads because they are so quiet but not many people use them because of the fees. You can easily get around without the toll roads, it just takes a little longer. Actually all roads are quiet here because there are only around 10 million people.
Car insurance I find to be very cheap probably because I have a long history of no claims and my advanced years but the big difference here compared to the UK (I don't know how it's charged in the US) is the cost is not at all dependent on where you live - it's based on you and the vehicle which is the same in Spain.
The cost of cars is insanely high in Portugal compared to most of the rest of Europe (including Spain), maybe because cars used to be seen as luxury items so the sales tax was based on ability to pay, for whatever reason it is still high. Importing cars from anywhere else makes no difference as the tax is applied on registration. I would take the good advice offered from Paulo and also suggest a van (because they are designed for the abuse and high mileage) if you intend to be in the boonies or into living partly off grid. The upside is that there is much less of a throw-away culture and consequently not so much negativity from owning a beaten up car - there is a lot of snobbery in the UK for example where your car reflects your status.
Renaults, Citroen's and Peugeot's' are everywhere because they are cheap to buy initially, they fall apart quickly because they are designed to but I'd also suggest a common brand as much as I hate them - because there are plenty of spares and people with experience working on them. If you want Japanese for reliability, again a commercial vehicle or a pick-up would be the best bet. Don't ignore diesel, it's a much cheaper fuel than gasoline and the engines are less complicated and generally more reliable.
Best wishes
Dave