No, running derailleur cables through another 4x~90 degree angle is bad for shifting quality (experience from other everything- integrated bike). As well as it is a nightmare to route the hoses through both the stem/handlebar as well as the head tube. There is space for the brake hoses but I'm already having trouble getting them rub-free. Let alone with another 2 through the same space.

The 2 wires outside don't bother me.

Aren't the bolts of some components already have thread locker applied?

For me, I usually apply thread locker to bolts for mounting, like bottle cage, pannier, and computer mounts. These area might rattle. The rattle will loosen the bolts. Loose bottle cage bolts will destroy the mounting points. I've learned the lesson.

I guess it is no problem to add thread locker in those areas. I've never needed it. I build the bike and then check all bolts @4 weeks and 3 months. If they have not loosened then, they will stay put for a while.

You are correct that some parts come with prepared bolts. The stem bolts on my ritchey stem came pre-thread-locked I just remembered, others did not.

One point I would advice thread locker is on the disc brake bolts if you use 6bolt rotors. Those bolts will come pre applied too.

And the tip to be extra super carefully not to get anything on the rotor is very good too

It could well be (a form of) plastic. The compression needed to preload the bearings is not much.

Cme can tell us

not bad for a commuterbike 

Cool, I really look forward to receiving the frame. Mine is a size 58 and also BSA. Can't wait to build it!

I'll be combining ultegra and GRX parts to get me a really flexible bike to use all-round and for holidays.
Curious to see how it will ride with the wheelset i just built with wide slicks for 'bad weather' (32mm contis, this is my road wheelset for the 696 gravelbike that's already in the stable  ). Road riding at 3.5 bar is increadibly smooth.

I know, but..well..."pictures or it didn't happen".

Thanks!

As soon as everything is in I'll have more pics 
Still waiting on the frame and gear to arrive

The fork on the right has another opening for for the housing or the hose to exit the fork, near the caliper?

Yes both, otherwise you can not attach the hose to the caliper 

0.75mm seems right, I'll update my post. 3 cross only.

571 erd according to spokecalc or DT gives 288/289 for front hub. You must have entered something like incorrect number of holes, try it again.
290/292 they suggest is close enough it would likely work with a short nipple, squorx, or with washers. But 16mm could be a problem.

For the front hub friction, there is a threaded ring on the non-disc side that sets preload. First undo the m3 screw locking it in place, then turn it clockwise to loosen it. You may have to hold onto the axle, but be careful not to crush it and use the wide section that is the strongest. Turn it back counter-clockwise until its just lightly finger tight. There should be no side to side play.

Quite a bit of friction is expected since there are 5 rubber contact seals inside. So it may already be ok.
While you have it open, can put some grease to protect the bearings, mine was barely greased on just one side only.

As an update to the friction part: everything runs smoothly after a few rides so it was just the bearing seals that needed some settling.