Market Indicators and other questions

1)Price alert placement on already holding stocks - some stocks I see alerts placed on high and low and some I see alerts placed on high and middle - pls clarify 2) I see often Cross Currents and Air pockets are mentioned. Request you to kindly explians what it means 3)do you use log scale or linear scale Charts? 4) Market Indicators:
1) Daily Market Average NYSE - Advance/Decline Line - May I know how many stocks are taken into account to decide Advance/Decline Line?
2) 10 Day Moving Average(NYSE/Nasdaq) Upvolume/Downvolume- May I know how many stocks are taken into consideration?