need help with sweep picking

[assmonk3y]

ok ive been trying to play canon rock. yeah i know its a lil overplayed..
but i need some help, especially from those of you who have nailed this song. i'm having problems nailing this sweep fast enough. it sounds very segmented after going from the 16th fret to the 21 fret up there. and do i barre and roll my fingers while playing the 14 14 14 ?

S S S S S S E E E S S S S E
---------------9-12S--17--12-------------------|
------------10----------------14---------------|
----------9----------------------14------------|
-------11---------------------------14---------|
--7-12---------------------------------12S-16--|
-----------------------------------------------|


|-----5-----|
S S S S S S S S S Q Q Q
--21-17-------17-12----------------------|
--------17----------14-------------------|
-----------18----------14----------------|
-------------------------14-------------|
-----------------------------12~---------|
-----------------------------------------|



on a side note

-9-12-9-21-9-12

if i were to Tap and pull off the above, do i have to pick the string first for the first 9 before hammering the 12?