I want to ask about when should you raise your finger during salah and when should it be lowered?
The Hanafi method is to lift the index finger when you reach “la ilaha” during tashahhud and to lower it once one reaches “illallah”.
The Shafi`i method is to lift it when one reaches “illallah” until the end of the tashahhud (until one finishes saying “rasulullah”).
The Hanbali method is to lift the finger then lower it again every time the word “Allah” is mentioned (thus doing it twice, ashhadu an la ilaha illallah wa ashahu anna muhammadan rasul allah) (al-Albani recommends this method too and says this has the most evidence behind it).
These three methods are the most common. From what I have read, none of these three schools recommend moving the finger repeatedly, one only lifts it then lowers it.
The Maliki method is to move the finger left and right (not up and down) repeatedly from the beginning of the tashahhud to its end. Some Malikis however say to lift it up and down.