1... yes you can have different sized blocks. on the top menu, choose help and search. look up Custom Set
2... sort of. design the center. choose a border. then add a second border. under border style, choose Blocks then add another border.
3... when you draw the block and color it, be sure to save the colorways in the sketchbook. after designing the quilt, be sure to save the quilt.
i use eq5 a lot and don't see the need to upgrade. however, i've never actually made a custom set design, just played with it a smidge... that's why i referred you to the Help section