We also had some discussion about this very topic here where you can configure your ini file to draw in ortho view.

Bit of a pain I know, but does work well.

http://moi3d.com/forum/messages.php?webtag=MOI&msg=6171.1

Those shapes you've drawn do seem like an ideal candidate for flow but if you've already tried it, then how about making your curved shape, giving it thickness and then drawing a temporary construction planes where you want the holes and then Boolean the holes.

Thanx) Kevjon, what does it mean draw in ortho view?

Draw a curve on a surface in ortho view.

Moi normally only allows you to draw a curve on a surface in perspective view.