Thanks for the comments, all, on the slide rule. My father (an actuary and math major in college) of course had one and used it, pre-calculators. I will see what I can find out about using them -- they seem brilliant. Hopefully I will be able to figure them out. Alpsman's comment is encouraging.
Regarding the typewriter -- no, I don't speak Portuguese at all, though I can figure out a little, just because it's a Romance language and I can "triangulate" from French/Spanish/Italian. I have a collection of typewriters and am embarrassed to say I focused on the typewriter itself and not the keyboard -- what are the chances it would be so different? So I didn't even notice until later.
First I had to figure out what the keyboard was; fortunately I have a reference guide. Of course it's fully usable for just the English alphabet, but touch typing is out of the question, considering how very different it is from the standard QWERTY keyboard. Apparently (according to Wikipedia) the keyboard layout dates from the mid-20th century, maybe instituted during the Somoza regime? Portugal long ago adopted the QWERTY keyboard, so this typewriter is a bit of a time capsule. I haven't checked the serial number but I doubt it's newer than the 1960s. I have no idea how it would have come to be in Hartford, CT (though there is a sizable Portuguese community of long standing here).
Yes, several of the diacritical mark keys are "dead keys" -- they don't advance the carriage (so a little planning is required, as you mention). One key I can't figure out -- it has a and o (underlined just as shown). I don't think I've ever seen these before.
Oh, I got the meter, slide rule and Olivetti for $40 total. The hunt was good -- the gods are pleased!