Have gained so much knowledge from members of this forum, so I'd like to share my experience in Brazil from a first timer's perspective, hoping my experience will provide a bit insight for other novice travelers. (Disclaimer: my experience is limited and i don't speak Portuguese, so take it with a grain of salt - )
Currency exchange - ATM fees are high and withdraw limit is low. At some places I felt comfortable using credit cards, and carried cash, both methods got me the best exchange rate, at least 8% more than any ATMs.
Power outlet - US plug won't work 99% of the places and I had to buy a power outlet converter.
Language barrier - for sure having knowledge of Portuguese is a major advantage. However without did not impede major activities for me. I bought a couple of offline translator apps but never got a chance to use them. Google Translate app did the job even with 3G connection. Only drawback is Google sometimes get the voice wrong or mess up a complicated sentence. But for most communication, it worked.
Transportation - Used radio taxi, regular taxi, uber and metro. Uber is by far the safest, especial for foreigner without Portuguese skills, fast, friendly and affordable. I had such a good conversation with a cute friendly 26 years old driver, I even got his number and email with the intention to hire him as my driver/guide.
Safety - all advices given by those experienced travelers on safety are good and should be followed. I personally felt it's safer than I expected at where I stayed. I saw a lot of restaurants open and people walking around in groups or family with kids after 11pm at Jardim area at São Paulo. Even at downtown Rio, after 8pm, there's still a lot of people waiting buses, including single female. As foreigner with limited Portuguese, sure need to be much more cautious than locals.
Therma Lagoa - São Paulo, Saturday night packed, probably 100 guys. I would consider half of them attractive with nice body, 10% my type. 70% muscular or athletic build, rest skinny twinks. Maybe 30% Spaniard looking, 50% mixed to a degree and rest African looking. Among the 5 people I talked to, 2 self identified as gay, 2 top only, 1 is pretty effeminate. All started with R$150, 3 would take 100 when I countered. One of the top guys agreed to bottom, however he was way too tight and made the I'm hurt faces and noises, so ended up doing nothing. The guy kept asking whether I'd pay him in US dollars as he liked it better and kept asking for tips. He ended up with no tips and only Brazilian Real. Other encounters were smooth. I was expecting to be approached from the guys, to my surprise, I had to take the initiatives half of the time even after eye contacts. The place is clean, and there's a sauna employee outside helping customers getting taxi and feel very safe at night.
It was much slower Sunday with maybe 20/30 guys, all from Saturday. Talked to a couple of guys and they all started with R$100 (supply and demand rules) and one even offered to do everything.
Thermas Fragata- the facility is older and probably needs updates. Guys are more twinks and African looking Brazilians. It was busier than Logoa on Sunday.
Monday - Meio Mundos - Rio, pretty busy with 40 or so guys when I got there around 630, and quite a few more checking in when I left around 7. Most guys there were African looking Brazilians with nice body and big dicks. Could be a heaven for size queens. I didn't like the locker I was assigned to as it felt like it could be easily broken in or manipulated, and they wouldn't give me a new one, so I walked for 20 minutes fully clothed and decided to leave. The entrance area is brightly lit, Maybe added by the owner as most street lights around are much dimmer, feels safer.
Tuesday-Club 117. Pretty busy with 80 or so guys, similar to Logoa in terms of looks and body types, maybe slightly older garotos. Guys here are more aggressive than Logoa, but will walk away after a nao. 2 guys who claimed to be versatile couldn't perform as bottoms. I kind of think they say that to get customers and know customers will give up/in eventually. 3rd guy I talked to is my type and active only, I really like him, so we agreed on a price for a little bit foreplay. After we did it for 2 minutes, he said time's up for a little bit foreplay. He pointed to the word a little bit that we agreed on when I questioned. So I ended up paying 100 for 2 minutes. Thought it'd last 15 min at least from experience with other guys, guess I set myself up to be ripped off by using ambiguous words. After that, there are 3 things I always want to be clear: how long, how much and what. 4th guy was really sweet and had a wonderful time.
Friday - club 117. Slightly busier than Tuesday, some new faces.
Saturday - club 117. Less busy than Tuesday. Pretty much the same crowd.
100 is generally the asking price in Rio. I do tip for people who try to provide good service to show my appreciation. But I stopped buying them drinks as I noticed the moment I offered the first guy, all guys asked me for drinks.
I'd say, for a first timer foreigner speaking no Portugese, 50% try to impress and are sweet, 25% do not try or do not deliver what they said, 25% will rip you off whenever they can. I bet things are better for regulars and Brazilians. Using a translator app might hurt, but I tried to keep it simple and short to avoid miscommunication or to offend them.
In general, it feels like a buffet, you have a lot of options, can dab into different types for a quick 15 to 20 minutes encounter, and share the same dish with other customers. It won't feel like a exquisite dinner at a nice restaurant for a full hour. Maybe next time will try online ones and see how that goes. For the huge population of Rio and São Paulo area, seems like the garotos population is not that much higher than comparable cities in population like NYC or LA metro area.