Poland is a nice and welcoming country in Eastern Europe according to the UN statistics division (and to many western europeans) even though most of Polish and Eastern European people tend to refer to it as "Central Europe".
A FB group to look for travel companions (not only hitchhikers).
Hitchhiking in Poland is definitely easy, fast and generally accepted by almost any kind of people since there is an old and deeply rooted hitchhiking culture throughout the whole country. Poland also has some of the most active hitchhiking clubs and competitions in the world.
Local urban transport is generally affordable even if it tends to become more and more expensive year after year.
A FB group for bus and truck drivers might be useful.
PKP's ticket/timetable sites (trains):
Hospitality exchange networks work usually very well.
Wild camping is mostly tolerated.
There's an FB group for hospitality exchange in Poland, but it's secret and you need to first know someone who can then add you. Just ask around.
Not expensive not cheap. Dumpster diving works usually fairly well around supermarkets,
Usually good wifi and often also internet cafes.
Even though you will see many buskers around (mostly gipsies), especially in touristic centres of cities like Wroclaw, Poznan, Krakow or even Warsaw; Poland seems to be not really the best country to busk in Europe.
The local currency (zloto, PLN) is not very valuable and generally people seem not to appreciate street art too much as in other neighbouring countries (e.g. like Czech, Germany or even Lithuania and Slovakia..(or maybe it was just Fede's bad experience..still in 5 cities..during 2 weeks)