Interpreting Technical Drawing Symbols: Φ75H7, 3×75°, M39×2 on Gears

Recently, I was looking through various technical drawings and came across symbols that I do not know what they mean, I will list them in subpoints and I would ask someone who knows what they mean to write:

1. Φ75H7 - what does H7 mean?

2. 3×75° - what does the 3 on the very corner of the gear mean? probably refers to three elements that have a slope of 45 ° but it is the corner itself and I do not know what elements?

3. M39×2 - also a gear, what does M mean? - well, M is the designation of the metric thread, or in the gear wheel too? and what do these two mean

If I notice dimensions that I do not know, I will add them

Thanks,

one more thing that can mean the diameter written like this:
for example:
1.23
1.28
the point is that these two values are given as diameter, how do you read it?