Spacing control of measures and double bar lines

I am using Notion mostly for writing out original jazz charts. I am looking to get more control how how many measures are on each line. I see I can request 2,3,4,5,6 measures per system on a page for Full Score or parts. But, sometimes I want 4 measures exactly and then I may have a measure of 2/4 and want 5 measures on the next line.
Also, at the end of the piece. If the last line of the score has only 2 measures it will stretch this out and look very awkward. Can I make the double bar at the end of the piece happen in the middle horizontally?
Also, in a 3/4 piece the ties are not working correctly across bar lines. And the spacing of 3/4 looks pretty bad. It leaves a lot of space at the end of the measure. I'm using Notion 3. Is this better in Notion 4?
Also, at the end of the piece. If the last line of the score has only 2 measures it will stretch this out and look very awkward. Can I make the double bar at the end of the piece happen in the middle horizontally?
Also, in a 3/4 piece the ties are not working correctly across bar lines. And the spacing of 3/4 looks pretty bad. It leaves a lot of space at the end of the measure. I'm using Notion 3. Is this better in Notion 4?