Both are correct buy there is a slight shift in emphasis. If you put the adverb before the verb, that is the normal unstressed position and if you put it after you are really emphasizing it. The difference may not show in the English translation.
"amaso"" is a pile. It works with things that are countable, for example ''amaso da terpomoj"" a pile of potatoes. For everything else use "multe". Note: if you forget "amaso" and use ""multe"" every time then you will always be right.
not exactly. In French there are strict rules that tell you when you can place adjectives before the noun. In Esperanto both positions are equal and correct, whatever feels better for you, usually the same place it would be in your native language