Quote Originally Posted by cegorach1
All what I want to say can be shortened two several points

1 - Balcan principalities were not the defenders of Europe, because they didn't stand in Ottomans way and didn't have enough resources ( money and manpower) to do it,
It really depends what period of time we're talking about. Wallachia and Moldova were considered important enough to warrant the "undivided attention" of 2 out of the 3 most important Turkish sultans in history. Bayazid I Yldirim (=the Lightning) and Mehmed II Fatih (=the Conqueror) led in person their troops into Wallachia (Bayazid I and Mehmed II) and Moldova (Mehmed II). None of the invasions ended up successfully. The Turks wasted on those occasions 3 of their largest armies which could have been used against other targets.

Besides the 3 above-mentioned attempts to gain control over Wallachia and Moldova, the Turks tried time and again to conquer the two with zero success. Each time the Ottoman empire would throw armies conservatively estimated at 50,000 - 60,000 men strong, each time losing at least half of those soldiers. Again that ment less troops for the other theaters of war.

Due to the net "score" in favor of Wallachia and Moldova against the Ottomans the two countries were never annexed. They remained autonomous and not very reliable vassals during the times the Ottomans were strong (paying tribute was less costly than being victorious but left with a devastated country) while at times they were independent or only nominal vassals. Bottom line, they were always something the Ottomans needed to worry about.
Quote Originally Posted by cegorach1
2 - Hungary and Hapsburg empire were the countries which truly stopped Ottoman advance,
Well, I'd say they were among the countries which stopped the Ottoman advance. Just to put the things into perspective, in 1526 the Hungarian kingdm is wipped out. However the Ottomans are left with an overextended right flank represented by Wallachia, Moldova and the newly independent Principalty of Transylvania. For example from 1525 till 1529 on the throne of Wallchia sat a king (Radu of Afumati) who fought 20 (!!!) victorious battles, most of them against the Turks. While a lot of those were probably just defeating Ottoman raiding parties that gives an idea about the kind of pain in the butt Wallachia was for the Turks.

Quote Originally Posted by cegorach1
4- Wallachia/Moldavia were primary interested in their own survival and independence when it was possible to reclaim it not in some crusades or other enterprises far beyound their resources,
He, he, it was enough for keeping the Ottomans busy elswhere, diverting important resources from the Central-European theater of war. From 1595 till 1599 Michael the Brave, king of Wallachia brought the war to the Ottomans, giving them a taste of how it feels to be on the receiving end. His actions triggered several revolts in the Balkans, giving the Turks some additional headaches and preventing them from pushing towards Vienna (which was first besieged in 1529).
Quote Originally Posted by cegorach1
5 - these states were mostly buffor countries between Poland and the Ottoman Empire rarely independent, mostly Ottoman or Polish vassals ( or both at the same time),
Yes, they were vassals indeed but the word doesn't actually tell the story. Both countries were not exactly obedient vassals. They were paying tribute (or not) but for the majority of the time that's all that was to it. Most of the times the kings pursued their own foreign policies. I've already mentioned that the Ottomans never managed to defeat them in a decisive battle. It was equally hard for the Poles to really control those countries for any meaningful period of time.
Quote Originally Posted by cegorach1
6 - One of major factors in lack of major conflicts between Poland and the Ottomans was the fact that it was very hard to supply any larger armies moving through Moldavia e.g. Chocim campaign in 1621, or Moldavian campaign in 1693,
Poland was not the main target for the Ottomans to begin with. The Ottomans were interested in controlling the major trade routes, hence their push towards the center of Europe instead of, for instance, trying to invade Italy. Besides, the 17th century is when the weaknesses of the Ottoman empire become manifest. A Turkish army drilled and equipped like the European ones of the time would probably not have failed to take Vienna. During the 15th and 16th centuries however, when the Ottomans were really strong, any direct conflict between the Ottomans and the Poles wasn't possible because of Wallachia and Moldova being in the way.