A: Yes, any H4 visa holder may switch to another type of Visa, like Student visa F1 or working Visa H1 while in U.S. However, you must qualify and fulfill the requirements for the particular visa category.
A: No. H4 visa holders are not permitted to work in U.S. Remember that as a spouse you will accompany a legally employed person in the United States on a dependent visa. You should not try to seek employment in the United States on the H4 visa.
A: In order to work in U.S. you must have a working visa status like H1B.
A: A spouse and children (age under 21) of H1 visa holder's can qualify for H4 visa.
A: The process is simple and there is no need to file a petition. You can directly apply for the H4 visa at the US Consulate in your home country.
A: Yes, you can study on the H1/H4 visa.
A: If your visa was not issued under Section 221(g) of the United States Immigration and Nationality Act, it means that your case requires further administrative action. It is not refusal per se. It only means that it is on hold.
Here is what happens
A: Absolutely. You are allowed to volunteer on the H4 visa. However, there is a catch. If you volunteer for a job for free, which is otherwise a paid opportunity, it will amount to an illegal activity. Typically, H4 visa holders volunteer with religious and social organizations. There are many organizations that require volunteers for their projects.
A threshold question is whether your volunteering qualifies for a paid job. If it does, refrain from doing it. If it does not, you should probably say yes to it.