I only bother with ESD protection if it is going to an external connector, R1 + R2, I typically use 22R in these positions.
I wouldn't bother with the test points which removes the warning for the "stubs".
I typically route diff and impedance controlled pairs / traces on the top layer, with the 2nd layer (inner plane) a solid ground, make sure the traces do not cross any other signal if you can help it, if you must, make sure it not a emissive source like a clock source etc. I wouldn't usually bother surrounding the pair with ground, just make sure I had good plane referenced.
To calculate, you can use a calculator with a known stackup, or you can ask for the track and gap from your usual PCB supplier for 90R differential, they will be able to tell you for their stackup what the values are.
If it is just for testing, then don't worry too much, just make sure the trace lengths are roughly the same length (for timing), for production i'd do it properly, if you plan on taking it for EMC testing then definitely do it properly!