In terms of weight, it will probably require a small amount of extra fuel to make a jump. But if your concern is speed (and iCouriers are great fun and can be very fast) then go with the smallest / lightest modules you can.
I'm pretty sure that power plants don't use fuel directly, I think they are actually a nuclear fusion power source.
It's your thrusters that use fuel, and if you are going for a fast iCourier, make sure you look into getting the enhanced performance thrusters.
There's links to a couple of builds here if you'd like to take a look at to give you ideas, but I'll put them in a spoiler in case you want to do it yourself.
I'm pretty sure that power plants don't use fuel directly, I think they are actually a nuclear fusion power source.
It's your thrusters that use fuel, and if you are going for a fast iCourier, make sure you look into getting the enhanced performance thrusters.There's links to a couple of builds here if you'd like to take a look at to give you ideas, but I'll put them in a spoiler in case you want to do it yourself.
Here's an example of a race iCourier
s.orbis.zone
And here's one that can actually be used for other things
s.orbis.zone
Coriolis EDCD Edition
A ship builder, outfitting and comparison tool for Elite Dangerous
s.orbis.zone
And here's one that can actually be used for other things
Coriolis EDCD Edition
A ship builder, outfitting and comparison tool for Elite Dangerous
s.orbis.zone
You can see right-bottom of screen numbers like 2t/hr and it changes in different modes. That is how much reactor takes to power up all modules.
I would say it depends on modules amount most.