I need to run a wire from a switch on the wall up the wall and across
the ceiling to a new overhead light. (Note that unfortunately, the
joists run perpendicular to the direction that I need to traverse the ceiling)

Doing so presents the following two problems for me:
1. How do I make the right angle turn through the top plate and into
the ceiling joist bay?

2. How do I go through the joists as I traverse the ceiling from the
wall edge to the center light location?

Note I don't have the option of using an unfinished attic or basement
to help me. I am trying to avoid ripping up more plaster than I need to.

I plan on buying a long flexible 1/2" bit which I believe should at
least help me with #2, though I'm a bit short on the details of where
I drill the entry and exit holes and how I achieve the right bend and
angle to go through the middle of the joist.

However, I am a lot more stumped about how I make the right angle
transition from the wall bay into the ceiling joist bay.

Could anybody give me some detailed pointers and/or point me to any
online videos? (I tried googling but found only general suggestions
such as using a flex bit)

Thanks