3 things i dint understand

Hey im new to trading and there are 3 things i havent found an answer to that i dont understand. First one is that in videos about trading it sometimes shows that when the chart goes down its a good thing? The second one is that i hear people talking about like asia and london and new york and stuff so is that like time zones or what? And third is what setting is best for candles minutes per candle? Thanks!