No. Polish Army was developed along the border because Polish politicians were affraid that if Germans had invaded only some parts of Polish territory (i.e. the Corridor, Great Poland and Silesia) and met no resistance, France and Britain would have tried to weasel out of their obligations claiming that if Poles themselves weren't willing to fight there was no reason for them to do so. Poles suspected, that had Germany occuped Pomerania without a shot and then proposed peace, western allies might have accepted it.
Correct.
Polish strategy was to bleed Germans in frontier battle, then withdraw to central Poland to the line of rivers Narew-Vistula leaving Great Poland and Pomerania on their own. Poles seriously underestimated mobility of German forces and influence of Luftwaffe on their own mobility, not to mention thousends of refugees escaping from Germans. Any bigger counterattack was considered possible only after allied offensive in the west.
Ditto. That was exactly the plan. It wasn't wise (trying to wage a fighting retreat with infantry divisions in the face of armored ones), but it was that.