Newbie Ask: 1) Select Object? 2) Rectangle line thickness 3)delete path node

[Fran3]

I'm running 2.8.22 on Windows 10.

I've watched a few videos and done some Googling but still have some questions...

0 - First I should ask... is Gimp vector based or a bitmap program or what?

1 - Once I create/design a shape with the Path Tool and go on to use the Rectangle Tool to create and Stroke a rectangle... 

How can I "re-select" the shape created with the path tool so I can perform additional edits?

2 - When I use the Rectangle Tool to create a rectangle and Stroke it as a Solid Line... say 5 px...

Why are the vertical lines of the rectangle wider than the horizontal lines? 

(Image area = 1,000 by 1,000)

4 - When I create a closed path with the Path Tool and switch to edit in order to curve the nodes... I saw in one tutorial you could click the node to delete it... but I can't seem to make that work... 

4a - How to delete node on closed path?
4b - Why when I go back to design mode on the path it seems to work like edit mode in that I can click a node and curve it?
4c - I can only seem to move a node by going back to design mode... right?

Thanks for any help.

Fran3