How does it work exactly ?

From map:
"# Crank is the %% boost of the map injection times right after start
# this boost decays to 0 over about 20s
"

Boost starts immediately after the engine starts to run/ignites?

The figures in V11/Cali maps, f e
10   20   30   35 C
60   60   55   50 % ,
where do they come from?

Well as soon as the RPM increases over that of the first column ( 500RPM ). The ECU switches from using the prime values to using map derived values.

Map entries are always adjusted by barometric parameters and by a boost value. This boost value is another 100% = 1024 type entry. The boost entry in the map determines its initial value and each power cycle decrements this value to 1024.

So a boost of 10% would be a value of about 1130.
After 100 power cycles its back to 1024.

The values in the map I came up with were to try and be a smooth transition from prime values to map values but this stategy may not be correct.

OK.

So, first 20 seconds after starting, how much fuel does it get at +20C?

According to our V11 map f e:
Is it 3456 ms (3rd tps, 1100 RPM), Air T +3,4%, Oil T + 18,8% & Crank boost +60%?
Or just Crank boost first 20 sec, then temp corrections take over?

First line is correct.