All phones have hands-free kits and the dealers are ready to install them but, most often than not, they are not really motivated to keep the original looks of the interior untouched.
Yes, it would have been more logical to combine the two reservoirs into one: as we generally use the rear window washer much less often than the front one, its reservoir is usually still nearly full when that of the windshield is already empty. You can improve the situation by connecting the two reservoirs together. Drill a hole into the sidewall of the reservoirs near the bottom. Fit a banana jack into this hole (don't forget to use some sealing gasket or silicone sealant before you secure it with a nut).
The GTi and some TZ trim level diesels have a four-function window regulator switch on the driver's door: regular up and down while you push the button, plus an automatic up and down to the appropriate end position with a single push of the button). It is easy to retrofit this unit to another model with simpler electric lifters: go to a salvage yard and find a GTi or TZx with this unit fitted.
If you have the original remote control fitted, the passenger's side door lock does not activate the central locking by default: the central unit has only two triggering inputs, so Citroën had to use the second one either for that door or for the remote control.
When you retrofit items not originally fitted to your car, you often have to tap into wires or make new connections not already present in the electrical circuitry. The best way to do that is by soldering. Although making nice soldered joints requires a little bit of training and experience, it's still far from rocket science. Practice here doesn't mean months or years, much more like five minutes, especially as we're not speaking about soldering delicate semiconductor components on multilayer printed circuit boards but a couple of thick wires...
The most likely cause is intermittent connection to a sensor (or possibly an intermittently failing sensor) which is OK with the car level and the wheels in the straight ahead position, but which breaks when wheels are turned or the body tilts.
Measure the impedance of each ABS sensor coil on each wheel with all possible combinations of suspension at maximum and minimum level and steering turned fully to the left and right. If that doesn't work, you could try detaching each sensor from the wheel and gently flexing the cable.
Undo the driveshaft nut (get someone to stand on the brakes while you do this, jack up the side concerned with axle stands, remove the anti-roll bar top swivel). Wire brush the threads as the nut disappears at the end, remove the steering arm and the brake caliper, tie them up, remove the hand brake cable bracket and the brake disc, remove the lower swivel, the driveshaft nut, the bolt holding the hub to the strut--be careful not to pull the driveshaft out of the gearbox or else you will lose the gearbox oil. Now you have the hub in your hand.
Avoid silicone based products, they are rather harmful, although it might seem different at first sight.
The long hydrocarbon chains that make up the rubber of the tires are attacked by both ultraviolet rays and ozone. As the molecules break up, the rubber loses its elasticity. The manufacturers use carbon black to protect the rubber against UV rays (this is why we only have black tires). A wax based protector is also used: as the tire rolls on the road, additional wax is forced to the surface and absorbes the harmful effects of ozone.
A tough question. It depends on your requirements, driving habits and, last but not least, the amount of money you are ready to spend. Many of us find Michelin tires to outperform other brands mainly because their different, softer composition is better suited to the suspension and riding characteristics of Citroëns. I also found them to last much longer than, for instance, the Pirelli tires of the same price and performance class I had on the car before. But all that having been said, you will find other BXers who left Michelin for another make and don't regret their choice.
This is a sure sign of air in the rear brake circuit. Bleed the whole system including the brake valve.