Various questions [Ender3v2]

[NoxArt]

Hello, I have a few questions regarding printing on Creality Ender 3 v2

1) At the start of the print the printer prints a straight line across one side of the bed - is this normal? Or some issue with levelling? (I don't mean the line that it prints around to-be-printed model)

2) Is there some was to influence the quality of the print? I printed the sample dog figure (some scuffing) and then my model - a cylinder with an extruded ring in the middle (but top side of that extrusion was not closed off / printed over, you could see the internal structure that printer does when filling in a continuous space - ATTACHMENT)

3) My last attempt with another cylinder ended up with the cylinder tipping over during the print - do you have any tip to prevent this? Right now I modified the model to add it a certain base which I then will try to file off, but what if this is not desired?
I was thinking of using something to fix the already printed part in place, but I worry I will move the model even if slightly.

Thank you