1 - Nicholas would continue to break the Constitution, bringing Poland more in line with Russia. However, with no November Uprising, the Congress Kingdom thrives. Furthermore, no rebellion probably butterflies away Constantine's death, so he continues to supervise the Western Gubernia's with their Polish language schools.
2 - there would be no "Nicholas' reforms". Reforms give you rebellions - see Decembrists.
3 - no idea how could the situation in Nederlands evolve. If Polish troops are deemed untrustworthy, Russians could arrive in the spring. However, Prussia would have no excuse apart from debt not to intervene.
4 - Crimean War on schedule
5 - No, Poland does not gain independence. This is possible only if Austria and Prussia both move against Russia. And neither has a reason to do so. The Polish Question = Too Big Can Of Worms. Austria - blocking Russia in the Balkans is one thing, inciting a rebellion in Poland - another.
Not having the November Uprising would be WONDERFUL! It avoids the destruction of the fighting and dismantling of Polish state apparatus. Come Alexander II and the "Post-Crimean Thaw" Poland would regain an elected Sejm and finally emancipate the peasants (they were free but landless, compelled to provide unpaid work in return for not being kicked off the land).