Would the following SQL remove also the index - or does it have to be removed separately?
CREATE TABLE #Tbl (field int)
CREATE NONCLUSTERED INDEX idx ON #Tbl (field)
DROP TABLE #Tbl
Yes they are. You can search in MSSQL help for CREATE INDEX article it is said there:
"Indexes can be created on a temporary table. When the table is dropped or the session ends, all indexes and triggers are dropped."