Sadly I can't help you with Rosalina, but yes, Melee being a faster game and all made it very fluid. You definitely felt like you had more control in timing sort of way. But yet not, since some physiques were overlooked. Being a veteran from Melee I'm more sensitive to things like, having to face the edge to grab it, having to press the grab button or shield grabbing to grab an item while I'm in midair, etc.
I love Melee almost more than Smash 4. But I most likely won't play Melee as much as I did before Smash 4 came out simply because I've run my course with it. Because, if you don't have Melee, you NEED it, and it might also seem better than Smash 4 once you get it if you're a competitive player like me who just loves to master every aspect. Then again, if you're just an average gamer who just likes to have fun, Melee will just seem like a bad graphiced, low content game.
Melee is fun on a competitive level, where there's so much to master and so much to perfect, it almost never stops. On the other hand, Smash 4 has so much more endless content, and online features, and things to collect and do that it will always be fun on a normal game basis. But yet compared to Melee? It doesn't have much that needs perfecting in the way that it is SUPPOSED to be a family pick-up game.