You can also start with a string and a vacuum cleaner. Put the vacuum on the exit hole and feed the string in the origin hole. Then pull the cable through tied to the string.
Here in the US it would be a better bet to go with these on Amazon. Better securing method as well to avoid any shearing issues. Unfortunate name on these ones though. ;)...
It looks like your hubs have removable end caps. This means there is probably through-axle end caps available for those hubs. Check on the hub manufacturer's website.
Try putting your other foot forward when you coast. Do you veer the other way? I find that a forward foot can cause a turn away from it sometimes. Try keeping your feet at a neutral position.
With drop bars you are also getting road bike brifter compatibility and hidden cables. The latter really not being an option at all with the Q-style bars.
It look like the bracket has two slots. Put the seat-brace end in the upper slot (where the extra skewer is in the pics), and you may gain another couple degrees.
To find 12, top of pedal stroke, is really easy if you have cleats. It's where the pedal is when you pull it back towards you as far as possible with the steering straight. Once you have 12, you will then know where the other times are.
The boom and slider must have been trimmed to pull the cranks back far enough for the seat position. Only the inside tube needed trimming though. But it looks like you still enough outside-tube anyway.