The bootcamp will be held in the modern building of University of Warsaw’s Institute of Applied Linguistics. The centre of Warsaw is easily reachable from Warsaw Chopin Airport (WAW) in under half an hour by trains and public buses, with a regular ticket for zone 1. The most convenient bus from the airport to downtown is line 175; there are also trains departing usually every 15 minutes, alternately to either Warsaw Central (Warszawa Centralna) or Warsaw Downtown (Warszawa Śródmieście) stations, which are actually connected by an underground passageway and only 3 minutes' walk away. Warsaw Central is slightly more convenient to change to other means of transportation.
Ryanair in turn flies to Modlin Airport (WMI), less conveniently located around an hour away in good traffic (it is in a different city). Please double-check your airport before getting your tickets - Modlin is not the end of the world; it is just more hassle (their Modlin Bus to the centre sometimes sells out, the alternative is combining a shuttle with a suburban train).
Useful information on getting into and around the city as well as its attractions can be found on Wikivoyage and Wikitravel. The core information on both websites overlaps - they usually differ in minutiae and feature uneven updates; your best option may be to quickly compare them and decide which one you like more. Ticket tariffs can be found on the website of Warsaw's Public Transportation Authority; a 20-minute ticket costs PLN 3.40, a single ticket (actually allowing unlimited changes within a 75-minute window!) PLN 4.40, a 24-hour ticket PLN 15.00, a 72-hour ticket PLN 36, and a weekend ticket (valid from 7 p.m. on Friday until 8 a.m. on Monday) PLN 24.00. These can be purchased at newsagents as well as from ticket machines at some stops and on many trams and buses, but technically you had better have your ticket ready for validation when you board as the inspectors doing the frequent spot checks tend to block the validation machines once the vehicle is in motion. You need to validate your ticket the first time you board the bus, tram, suburban train, or go through the metro turnstile. 1 Polish zloty is worth roughly a quarter euro/dollar.
The legal tender in Poland is the Polish złoty (PLN), equivalent to around € 0.23, $/CHF 0.26, or £ 0.21. With very rare exceptions, that is the only currency accepted around. Since airport exchange rates are unfavourable, you may want to get some PLN back home, exchange money in downtown Warsaw, or use a multicurrency debit card such as Revolut. While card terminals abound, loose cash still comes handy in some places.
The participants will be responsible for their own accommodation and arrival arrangements. Warsaw has plenty of lodging options from CouchSurfing and AirBnB to hostels and luxury hotels, many of which are conveniently located within walking distance to the school venue. Standard and quality can vary; the ratings on travel booking websites such as TripAdvisor, Agoda, Booking.com and others help.
Given the early starts of each school day, for convenient access accommodation options are recommended which are within easy reach of the central campus of the University of Warsaw (ul. Krakowskie Przedmieście 26/28), whence it is a brisk 7-8-minute walk to the event venue, or of Castle Square in the Old Town (12-14 minutes' walk away). As June is busy season in Warsaw, you are advised to book your accommodation early.
For short-term weather forecast you may check http://m.meteo.pl/warszawa/60 So far we are expecting summerly weather of daily highs between 26-31°C (79-88°F) and nightly lows between 16-20°C (61-68°F).
The electricity socket/plug type is the European C/E/F standard. Please remember to bring an adapter if you're coming from a different region.