So I got a hold of a copy of Daniels Siemens' 'Stormtroopers. Its not as detailed as i would like ( eg membership numbers are sparse) but it a least gives an overview of what happened.
The SA lost a bunch of members after 1934 but still managed to remain relevant even beating the SS in gaining control of the shooting and riding clubs in Germany . Continued serving as jackboots against the "untermenshen". They were heavily involved in propaganda and political education of the civilian population during this period. Formed branches in Austria, Sudetenland, Memel, Danzig laying the groundwork for thier annexations. Had a plan for the creation of SA villages colonizing the conquered Eastern Territories. Very few of these villages came to pass.
Suffered an even bigger loss of membership when WW2 started as all able bodied men were drafted. Those that remained behind became the manpower behind auxillery police, air raid wardens, first aid units. They also formed what were effectively einsatzgruppen in Poland before the SS formed actual einsatzgruppen during Barbarossa. After 1943 they were given a bigger role in maintaining public morale and rooting out defeatists. When the Volksturm were created in 1945 it was the SA that oversaw the training , equipping and leadership of these units though the Replacement Army was in operational command.