I want to tell you abouthow a bald man with an amusingly sounding surname ( funny-sounding last name) achieved outstanding success.

"Funny-sounding" is very common and quite natural here!

It shows that there are no reasonsis nothing in life that can truly prevent success.

Your sentence is correct, but "nothing in life" sounds a bit more natural.

He was a simple schoolteacher, but he became the number one business coach in Russia.

He is also one of the ten best public speakers in the world.

I am particularly impressed by his ability to set prioritizes wisely and take reasonable risks by delegating routine tasks at the beginning of his career.

Your sentence is perfect, just suggested a slightly more succinct phrasing.

Beyond his career, Gandapas has built a large and happy family, where he andith his wife are raisingnd four children.

Rephrased this to sound a bit less clunky.

I want to tell you about how a bald man with an amusingly sounding surname (funny- sounding last name) achieved outstanding success.

"sounding" only takes adjectives. No adverbs

ItHis story shows that there are no reasons in life that can truly prevent success.

"it" doesn't really refer to anything that makes sense here, gotta state the subject clearly

His life story inspires me a lot (greatly).

"His life story inspires me greatly" is also correct

He was a simple schoolteacher, he who became the number one business coach in Russia.

It seemed foolish and extravagant (wasteful ) at the time, but it was a shrewd move that ultimately paved the way to his success (that eventually led to success).

Both wordings at the end of the sentence are correct. I don't think extravagant really fits here

Beyond his career, Gandapas has built a large and happy family, wherein which he and his wife are raising four children.

Honestly, still sounds kinda odd to me... I'd completely rephrase the sentence
"Beyond his career, Gandapas has built a large and happy family with his wife, as they are now raising four children."

I want to tell you about a bald man with an amusingly sounding surname (funny-sounding last name) who achieved outstanding success.

It shows that there are no reasons in life that can truly prevent success.

Using "It" suggests you are talking about the story, but because you didn't really mention it before, it sounds like you are calling the man "it", which can be perceived a rude. Most likely you are referring to the story.

His life story inspires me a lot (greatly).

His life story greatly inspires me

He was a simple schoolteacher, he became the number one business coach in Russia.

He started as a simple schoolteacher and became the number one business coach in Russia.

When the money he earned was barely enough for his own lifeto live off of he hired an administrator and a driver to create an atmosphere in which the brain could work productively instead of doing routine tasks that took a lot of time and energy.

It seemed foolish and extravagant (wasteful ) at the time, but it was a shrewd move that ultimately paved the way to his success (that eventually led to success).