Electronic – What are markings on top of electrolytic capacitors

Generally there are two labels on most caps.

The first is the value, which is written:
<Digit><Digit><Exponential Notation>
It's generally in picofarads.

The second is the TempCo, or Temperature Coefficient. There are two common specification systems, namely EIA Class 1 and Class 2. This is the mysterious second label in most cases. It's generally written:
<Letter><Number><Letter> (though there are a few variations)
There are a few common tempcos - NP0/C0G, X7R, X5R, Y5V, Z5U

Tantalums, and bigger ceramics often also have the voltages:
<voltage number><+ or v>

Therefore:

• 104 K5K (small )
  The value is 10e4, or 100,000 pf / 0.1 uF. The tempco is not standard, may be manufacturer specific/extended range.

• 10 (box box, perpendicular right upermost corner) 35+ (Tantalum Cap, bigger variant of the last one)
  Need a picture to be more specific, it's very likely a 35v rated cap, from the 35+.

• 154 C1K (what is C1K, some other notation to Wikipedia?)
  Capacitance is 15e4, or 150,000 pf / 0.15 uF. Looks to be a Class 1 dielectric from the C1K. Is this a large cap? the tempco is very good.

• Orange Ceramic 333 K5X (what is 5X? X roman numeral?)
  33e3, or 33,000 pf / 33 nF. Tempco is either manufacturer specific, or incorrectly read.

• Brown Circle Slit 10n (no other marking, what is the op.temp?) (Diameter: 7.5mm)
  10n very likely means 10 nf, or 10,000 pf. If it's ceramic, it's probably 50v. Likely a cheap part, if the voltage is not marked.

• 27J 100V (what is 27J?) (Diameter: 4.9mm, blackdot on the head)
  Voltage rating is self evident. J is the multiplier, and I think there is a standard for letter multipliers, but I do not remember where to find it.

• Blue Slit Square (triangle) 104K X7R50 (What is triangle? X7R50? Operating V?) (side = 4.9mm)
  10e4 is the value - 100,000 pf / 0.1uF Tempco is X7R. the 50 is likely the voltage rating.

• 104 (side = 2.6mm, op.V? Tolerance?)
  10e4 - 100,000 pf / 0.1uF. Voltage is not known

This is kind of a guess. Anyways, it should show how this sort of thing works. Older parts may vary wildly, and it's always just a guideline. The best thing to do is find the cap's actual datasheet.

A lot of the parts have unusual tempcos. Is this a automotive/extreme duty part which contains these components?

The W is for Working; WV = Working Voltage