Shame on me for failing to mention the museum, and thank you for doing so.
To partially make up for my omission I’ll add that there is an annual fly-in at the EPKC airfield which is part of the museum (the field was established in 1912) and normally not in use. The 2016 edition is June 25/26.
I got response from EPKK, everything is ok. They instructed me to contact handlers (I guess handling is mandatory) Welcome Airport Services Ltd., LS Airport Services S. A. and Excel-Handling. Any recommendations?
The same question for refueling (Baltic Ground Services PL sp. z o.o. and PETROLOT Sp. z o.o.).
In addition they recommend contacting Polish Air Navigation Services Agency for navigation services. Is there any reason for contacting them?
I don’t see any reason to contact PANSA, especially if you’re flying IFR, we’re not THAT far east, even if Jeppesen would have liked to disagree ;)
If you want the PANSA VFR charts for any reason, let me know.
No idea on the handling / fuel, but my intuition would be to base the choice, especially of fuel, on price. You might want to check if they won’t charge extra for buying less than 1000l and “outside of fuel station hours” whatever that may be and plan accordingly.
Thanks for the tips. I’ll send them e-mails with my plan details and ask for pricing. No need for VFR maps.
Handling, landing and fees:
- Excel handling €185
- WELCOME Airport Services €75
Guess who I chose 
Excel for their excellent service above and beyond?
So initially quoted €75 turned out to be €117 at the end. I paid the invoice without questioning it (because it was in PLN and I didn’t bother to calculate prior to take off) but I sent an e-mail requiring explanation.
However, more rubish I got from Orlen – they charged me additional €42 for fuelling less than 1000 liters, so for 100 liters of Jet A1 I paid €142 instead of €100. If had known for this surcharge I could’ve simply put some more fuel in Zagreb and avoid refueling in Krakow (only two hours flight).
Emir, I find using UVAir fuel cards (I am sure others work too) helps a lot with this sort of thing as the website lists these extra costs. For EPKK Orlen it says: A small load fee of approximately $55 USD will apply to uplifts less than 264 USG.
Small fee of 42% 
in my case. Does this fee apply if you use UVAir card?
Regarding handling, I got explanation – I was charged €20 more for handling by mistake (will be refunded) while longer parking and unplanned pax on departure caused €18 of higher airport fees.
