Can you use "by" with only a noun?

BoSsSyCan I use "by" only with noun to mean "a method or a manner"?

Sometimes.

Let's go there by bike.
Very talented musicians can play by ear.
Some people believe you can learn computer programming by example.

BoSsSyFor example:You can learn a lang

To change the topic.

Can you eliminate the word "by" in some sentences.

Examples

"Rudolph masters the piano by practising hard everyday." Can you change it to:

"Rudolph masters the piano practising hard everyday." Would this sentence be wrong grammatically even though it makes logical sense. Could it also be written "Practising hard everyday, Rudolph m

I'm confused between gerund clause and a participial clause. How do you know which is which? Can the same clause be both depending on its function in the sentence

Consider:

"Practising hard, Rudolph masters the piano." Here "practising hard" is a participial clause modifying Rudolph, is that correct?

But same sentence rearranged....

"Rudolph masters th

Thanks. This helps