I know that both prepositional phrase and present participle can be adverbial modifier, but how should I decided which one is should be used when they were used to show a particular method or way of doing something. As in the following two sentence.
Those are some of the reasons why the father told his son, "Always give your wife what she wants." And why he also issued these words of caution, "Always treat her as you would treat a queen." That's because relationships can swing both ways with equal force. You can avoid a lot of problems by giving in to her, and you can also cause a lot of problems by giving in to her.
You can make a lot more money using the bank's money, and you can lose a lot more money using the bank's money. So the price to pay is an investment in your education and several years of experience.
1, Can I put the word by in the second sentence right before using?
2, How to decided which form is the most proper one to choose when using them as adverbial modifier, gerund or present participle?
3，Can I remove the word by from the first sentence?
4, Is the present participle phrase in the second sentence indicates in which way and method, or time?
In general, I don't think I can remove the propitiation by in sentence 1, but just don't know how to explain it.