Thanks you guys, now I understand the purpose of this "cheat mode" 
(By the way, is there a way to set a conditionnal order in task groups for using by default by all the newly created task groups (like if less than 20% fuel go refuel to colony)?).
No, however it is possible for newly created ships to be put straight into a task group containing orders, i keep accidentally sending my shipyard taskgroup off on training then later when i pull the ships out into their own task group the "shipyard taskgroup" ends up having no ships in it, but is still considered to be located at the point in space where i left it, new ships created into that task group then have to haul themself over to that location before they'll respond to my other orders, it can create problems especially when another new ship is created in that group later so the group is split in 2 locations, the group will wait patientlhto the group and combining midway. The solution is rather obvious, Either, don't order your shipyard taskgroup around the galaxy, or ; delete the offending taskgroup after a screwup (you can't delete the taskgroup if you're making ships into it though), or ; keep one ship in that task group so you can move it back to sol, then split all other newly created ships off the task group so it doesn't get locked up waiting to reform.
It's a bit micromanagey, it can be easier to just create your taskgroup and assign all it's orders before all your ships have even been created, the first ships will just wait around for the rest to be built and then they'll all go off and do their thing. It's slightly less efficient though because you could have the first ships doing stuff while waiting (unless the whole group will be built at the same time anyway).
</wall of text rant>
Also in the upper left of the map itself, as you zoom in or out there's a number like "65 m km" above a green line - that's how long that line is at that zoom level, which is pretty handy for a rough yardstick. And SOME of the sensor/fire control/weapon range circles show the radius in km.
Thank you Dr strangelove, for some reason this never occurred to me.