First thing first, PT-91 is never brand new, it is the upgraded
version of their T-72M1, Russian export version maufacturered by
the Poles.
( somethimg like our AMX-13, after the upgrade, we called them
SM1)
B4 the breakup of Warsaw Pact , the Poles has I believe more than
1000+ T-72M1 in svc, after that they joined Nato, started to
retired their T-72, still no Leo 2 then.
Currently I think they have abt :
T-72 597
PT-91 TWARDY- 233
Leopard 2A4 128
http://www.wp.mil.pl/index.php?lang=2
The T-72 and PT-91 has all been upgraded using Nato standard comm
set , so actually there is no qn on compatibility issue, except
they are not using the same ammo, but they can certainly fight
along eachother, so dun talk abt they got the Leo 2 so to be
compatible with other Nato nation.
Leo 2 is still better than their Popping Turret T-72 tank, that is
proven with fatal flaws discovered during GW1:
1) the crammed turret of T-72 with tank ammo found all over the
place , has resulted in ammo cookoff whenever the turret is
penetrated, causing the entire turret to be "popped up", killing
the entire turret crew.
2) The 2A46 gun has proven to have less effective range and
accuracy as compare to L44 gun, that gun only has a effective range
of 2km whereas the L44 gun has even destroyed a T-72 at
3.5km!!!
Anyway , the German practically gave the Leo 2 away, the Poles was
reported to be paying only for the transportation and refurbisment
the 128 Leo2A4.
So your Ist qn, how could the Poles refused at such low price for
one of the best tank in the world.
The answer to your 2nd qn is a definite YES!!!
The answer to your 3rd qn, is a yes German practically gave them
away, but Leo 2 is certainly more capable than their own
PT-91!!!