Are there any references of flags for Polish infantry regiments available somewhere?  I notice a lack of such flags in the store, so I assume that sources are hard to find.  Worst case scenario, I can always forgo their command strips.

There are no references for infantry flags that I have found, and I've been looking for a lonnnnnnng time!   You are down to variants on the Polish red/white flag and various clan/tagma symbols.  Look at this way, if you down this route, no-one can definitively tell you that you have it wrong...

There are some flags here from the early 17th century. I don't think they are 100% accurate but should give you some more ideas on what to do.

As Peter has said we have no information and so you can be creative.

https://www.1-72depot.com/wargames/28mm-polish-renaissance-cossack-flags/

Thanks for the responses, it does seem by my research that this era is lacking in definitive examples.  While I have your attention, I'd also like to see whether the Haiduk or "Polish" figures would be the more common uniform type in the 17th century.

On the Haiduks it depends on when you are talking about - it changes over time. Polish infantry was mainly German style until circa 1670 - i.e. they looked like German/Western troops. After 1670 they all changed over to 'Haiduk' style.

hwiccee, thanks for the info!  So before 1670 the "standard" uniform would match the GNP11 pack best?  Also, from what I've seen the Polish had a smaller ratio of pikes in their infantry lines (with more normal ratios in their "foreign" infantry).  Would you have any sources on what those ratios would be? 

Finally, I've read about Polish troops carrying a musket and axe.  It's hard to see on the store page here, but do you know if the figures are carrying them?

The figures do have axes, and they're really easy to paint. I've just posted a pic in the 6mm Facebook group of a battalion of Polish Musketeers, if you're on Facebook? 

re. infantry flags, saltires were commonly used, and horizontal stripes in various colours, in the latter 17th century so I think they'd be appropriate (and it's what I'm planning on doing) Wikipedia also has a lot of Polish/Lithanian family crests from this period which I'm guessing could also be used.

GenWAnders: Sorry it has been a while since I got the Poles and I answered without checking :(

OK so they had 4 types of regular infantry during the century. 

'Foreign' regiments which dressed like Westerners or were Westerners - i.e. you will need figures from the TYW, ECW or Sun King ranges. These were actually mainly Polish personnel and the bulk of the infantry until circa 1676.

'Polish' regiments dressed like GNP11 and are from after 1676. They basically replaced the 'Foreign' regiments.

'Hungarian' regiments (i.e. Haiduks) were dressed in Hungarian style. There were around all the time but in small numbers - and getting smaller as the century went on.

'Imitation Janissaries' which looked like the Ottoman originals and were special units raised in the 1680's - they were small and didn't last long. You would use the Janissary muskets from the Ottoman range.

With the army you should remember it was not regular as we would think about it. So the composition of the units could vary depending on what the person who raised it wanted - i.e. the number of pikes. The 'Foreign' units seem to have had the usual pike/shot ratio, but bear in mind that changes over time.

I personally don't think there is any conclusive evidence about what they did with the 'Polish' regiments & also it probably changed. It was for example common for Austrian armies to not use their pikes when fighting the Ottomans. They often used stakes, chevaux de frise, etc instead and I would guess the Poles could also do this. If they did use pikes it would probably be at a lesser ratio but then by the 1670s many armies were using less pikes. I have seen 1 pike in 8 but also 1 in 5 or 6 or even 1 in 3, also of course no pikes at all.

Craig, just to confirm do both GNP09 and GNP11 have axes, or just one or the other?

And hwiccee thanks for the wealth of information!  I'm thinking that my main force will be German-style, with either a 1:2 or 1:4 Pike-Musket ratio.  Then I may toss on some Haiduks for flair.

Now to figure out the Swedish forces...

I think only GNP11 have pikes but I don't have any 09 (yet) so not 100% on this. 
ive also got a Swedish starter army which I'm deliberately keeping locked away until I've finished the Poles (or as finished as any army ever is)