How much tetsing is required for April 2013 Application CPU patch ?

Problem Summary---------------------------------------------------
How much tetsing is required for April 2013 Application CPU patch ?

Problem Description
---------------------------------------------------
We are planning to apply April- 2013 Application security patch, as per Note-Id Oracle E-Business Suite Releases 11i and 12 Critical Patch Update Knowledge Document (April 2013) [ID 1530756.1].
From the driver file we could understand that the main affected modules will be as following:

ad
ams
amv
bis
cs
csf
dom
fnd
ibe
irc
jte
pay
per
au
bne
eng
jta
ben
atg
ieu
csk and some other.


Can you please explain

1.which all are the changes to be made by the patch?
2. How much testing is required for this patch?