I like bar end shifters, then your choice of road brake levers is wide..
Tektro Campag like ones are popular, they include the push button QR.
to make wheel removal simpler..
Shimano offers indexed, right side, bar end levers 8 speed or 9 speed.
the 8 speed, can work with a 7 speed, given the spacing is 7+1..
9 speed is thinner spacing to fit in 1 more cog in the same width.
the left is not indexed, a good-thing ..
will any/all of the cables need to be changed?
Yes.
It's better that way, so the breakdown clock is reset to lowest possibility.