Hi and welcome Darja! Great to have you "on board"

Do you use this Total HYDRAURINCAGE?
Yep, good stuff!

Do you prefer new spheres or just refurbished spheres?
I nearly always fit new, unless the sphere is a genuine unit in which case they usually re-charge well. If it's an AMTEX sphere I just throw them in the bin

Why your bxs don't have the the upper case-
http://www.bxclub.cz/graphics/dynamic/1715554_7.jpg we have it on the left side
Economics or because we are british I suppose!!!???

Do you have any problems with clutch kable? It must be tweaks because of you're sitting on the other side
Clutch cables can break but I dont think it afflicts BX's anymore than other cars. The pedal box design is rubbish but the box is no different ona LHD car so it's the same for us all!

and it's almost imposible to get electric right mirror (letf is really often in BX), do you have it, or it's just manual?
Over here the drivers mirror was nearly always manual, except as an optional extra or standard in the case of the P2 16V. passenger mirrors were options on most BX's and standard on higher trim spec cars

And in 16v: rider's seat - you can change position of the whatyoucallit on your hips, do you have it too?
You can adjust the lumber support and the "wings" that grip your ribs, the base will also tilt but I've never seen one that adjusts on your legs over here??
And I was very surprised, that in France 16 soupapes hasn't back electrik windows, it's the same in your country?
Blimey, for once the english got better spec than the french!? All 16v's had electric windows all round over here, and TZD's too!
Cheers
Chris G