About the pitot probe on the rear wing endplate: I think they are using it to have a more acuurate measure of yaw-rlative wind angle at the back of the car.
I think they have to ake into account the amount of lateral deflection the two exhaust plumes get in cornering: in yaw the windward plume will be deflected to the inside, and the leeward plume to the outside. Prabably they are trying to asses this effect on track compared to thier design data.
The two undercut chaneels could have a influence on this behaviour too. One could imagine the massa flow turogh the two of the m being slightly different when cornering, thus influencing / adjusting the difference in sidewash effect for the two plumes.
I do not think this exhaust solution on rbr is a reaction to what they saw on other cars : thy seem to push the envelope further.
The detail of the bodywork before the exhaust pipes exits is very interesting: i do not know what loophole in the regs they have exploited to carve two small edges on the surface, but, as another poster has already pointed out yesterday, the shape they have clearly is reminescent of a ncas intake.
In a naca intake the edges are sharp, with the aim of porducing two counter rotating vortices whose doenwash forces the air into the intake. In this cas the two vortices force the flow don towaqrds the exhaust for stronger interaction.
Also the elbow shape in the "coanda channel" is very interesting.
The undercut hole could be the famous "half a second trick" rumored about by jose luis tweets last month.
Front wing : I have no idea atm.