Well, there are tons of web sites about business etiquette out there, and I found one that was of particular interest.
There is also a lot more here. The person who puts this together, did a great job, but I wonder how old this information actually is?
Here is what he had to say about punctuality:
Punctuality is not an important cultural trait. It is courteous to arrive five minutes late and definitely bad news to arrive before the agreed time. Quarter of an hour late is not usually noticed. Over half an hour begins to be rude. Nevertheless, the Portuguese are usually aware that foreigners operate differently, so I would still recommend being on time [plus five] and 'phoning in' if you're delayed. Just don't expect your contacts to follow the same rules.
Ain't that the truth. Even in non-business activities.
About how to dress:
Long sleeved shirts/blouses are important, especially for men. Only foreign men wear short sleeved shirts with a tie.
No one, regardless of their nationality should wear tie with short-sleeve shirt, but whatever, still interesting - something I wasn't aware the Portuguese paid attention to.
The Portuguese understand Spanish but not vice versa, because Portuguese pronunciation is especially difficult, even though the written languages are similar. However, if you use Spanish, they will usually reply either in Spanish or in Portuguese with an attempt at Spanish pronunciation [which makes it easier to understand].
...even in business. I thought this only happened on vacation.
There's a whole lot more on there. This person has definitely put a lot of effort into this and it's worth a read especially if doing business in Portugal is of interest.