Just got a 3d Printer - Couple questions

[Cougar281]

So I think part of my issues have been with the slicer. I was using Cura version 15.04.6 as that's what was specified for Octopint, should I want Octoprint to slice the file. But I ran into issues with Cura 15.04.6. My first prints with it were messed up once they hit the 'top layer'. I re-printed the same item but using Cura 3.0 vs 15.04.6, and when printed using 3.0, it printed properly, wheras the slicing via 15.04.6 failed. Now, I printed using 3.0 and PETG, but I have a STRONG suspicion that if I re-slicded it for PLA on Cura 15.04.6, the end result would be essentially the same as that with PETG.

Any thoughts on the differences between Cura 15.04.6 and 3.0 in this regard?

Edit for a little more info - It was definitely something to do with how Cura 15.04.6 was slicing the file. When I went back and re-sliced the STL file and looked at it in layer mode, the bottom layer was goofy - it was trying to fil in a cavity in the middle that was supposed to be empty, and the top layers were 'frazzled'. Didn't look right at all in the slicer. The same view in Cura 3.0/3.1 looked fine and normal, and the results upon printing were good.