Travel / Warsaw to Cracow trains [7]

EIP are the fastest ones, but:
1) not much faster than IC - it's a matter of minutes
2) much more expensive than IC
3) If you choose IC, you will have as modern trains, as in the case of Pendolinos guaranteed, e.g. Stadler Flirt (ok, 99%-guaranteed, sometimes a new model has a malfunction and they may provide you with an older - but renovated - one).

4) If you choose IC, check the traveltime. It should go straight to Krakow, with three stations between them. If you see Kielce there, this connection will be slower.

Trust me, I'm an expert on Polish trains ;)
Btw - when you come to Krakow, check KrakowCard. It's a cheap tourist pass with a lot of free museums and unlimited public transport provided. krakowcard.pl

Travel / Poland trip in September - Zamosc, maybe Krakow, Gdansk, Warsaw, Wroclaw... need recommendations [15]

If I were you, I'd spend more time in the broadly defined area of Krakow. Krakow itself has got a nice city tourist pass that enables you to visit 40 museums and use the public transport when you're there (using a car in larger Polish cities isn't recommended, especially in the area of old towns, there's a lot of pedestrianised streets, etc.). There's, except for Wawel Castle and Leonardo da Vinci's Lady with an Ermine, Schindler's factory and Krakow Underground Museum, scenic Tyniec monastery recommended for a visit. You could take a walk there, too - the route leads along the boulevards. A lot of Jewish heritage to discover in Kazimierz district of Krakow (synagogues, cemeteries, dining facilities). Krakow is close to Auschwitz Concentration Camp and Wieliczka Salt Mines, there are a lot of tour operators providing trips to both places within one day. And I think having a guide when you are in Auschwitz is rather obligatory. If you like nature, think of a short trip to Ojcow National Park, it's going to look beautiful in autumn. Zakopane is further away but has the nice peaks of Kasprowy Wierch and Giewont that you may use for your hiking activity.

Travel / Footwear in January (Krakow, Poland)? [8]

Provide yourself with thick-soled shoes or boots, this January welcomed us with loads of snow and occassional temperature drops below -20 C.