Firstly, there is a Carrefour express down the street. Walk out of Sabinki, turn right and head straight for 5 minutes. You should see the sign shortly. But that is pretty small, like an fairprice express if you have been to one.
Another one to go is at Central. Take the tram towards Centrumm. The stop is near the university.
Take either 17, 33 or 41. It only takes 8 minutes to stop at DW Centralny. From there, walk downstairs, turn left, head down, turn left again, past the train platforms and head straight down. There is a Carrefour market at B1. It is about the size of the old Carrefour at PS, but just the market section, not the pots and stuff.
A third one that I know of is at Arkadia. This is a 15 min tram ride with the same trams as above. Stop at first Rondo Radoslawa because there are two.
From there, just head for the word Arkadia. You can't possibly miss it. At Arkadia, there is a huge ass Carrefour that is bigger than the Giant at IMM, if you have been there. It is just massive.
Apparently, there is also a TESCO at the end of the line, but I do not know if it is the tram line or the metro line. Most likely the metro line. It takes 30 minutes to travel there and I don't really see myself travelling there for a mall, even if the prices there are cheaper.
Internet
Wifi in Sabinki totally sucks. Your iPhone can't connect, and even if it can, you can only go google and your apps don't work. Your laptop takes several tries to connect, and your best bet is the LAN port in your room. However, there is only one port (the other port is a telephone line port), so you have to share with your roommate. Alternatively, you can bring a router so that both of you can have Wifi, but routers are hard to configure. I spent one whole day configuring mine to no avail.
Since your iPhone can't connect, you need to buy a prepaid sim card. Don't buy from Play (a telco). While the 5 pln sim card that gives 450 mb sounds cheap, you can only use it for 7 days, even though the 450 mb has an expiry of 3 weeks. That is because there is a prepaid card expiry and 3g expiry. To extend your prepaid card expiry you have to keep topping up - 5 pln for 5 days, 10 for 10 days, so on and so forth. So you have to keep topping up your card just to use your data, and the amount that you top up is locked in the card since you will not spend that much on 3g anyway as 1gb for 30 days cost only 10 pln.
Thus, you can consider buying the 5 pln sim card every 7 days, which costs 20 pln a month. Or you can take the Heya card that is in your orientation package from the university. There is a preloaded 20 pln value in the card, and you can go to T-mobile (in Central/Arkadia) to get them to purchase 1 gb for a month at 15 pln.
Transport
Once you get your student card from the school, you can use it to buy a 3 month transport pass for 150 pln (or is it 110, can't remember). It covers metro, bus and trams. But I am a cheapo so I didn't get it even though my friends did. What I did is that I jump the metro, bus and trams, which can be rather risky.
Money Changer
You can go to Warsaw Central to change your money. Most money changers will be ok, since the difference in their rates is normally zero point zero something, so it is a few cents difference unless you change a few thousand euros into zlotys.
Citibank
If you are planning to open a bank account, the best would be to open one with Citibank. There are several Citibanks around. One is in Warsaw Central. The other is at Galerie Mokotow, which is a 10-15 min bus ride away. Or you can walk about 20-25 mins to another Citibank. Maps for both are below, direction of the bus is also indicated.
