What does Skype use all those permissions for? I'd like to know what Skype does with all the permissions it asks for. 
Is there any page where Skype (the company) justifies the various permissions?

Does it make any difference, whether I'm a paying customer or not?

The permissions are as following: 


Your accounts

act as an account authenticator

Allows an application to use the account authenticator capabilities of the AccountManager, including creating accounts and getting and setting their passwords.

manage the accounts list

Allows an application to perform operations like adding, and removing accounts and deleting their password.

use the authentication credentials of an account

Allows an application to request authentication tokens.


Hardware controls

change your audio settings

Allows application to modify global audio settings such as volume and routing.

record audio

Allows application to access the audio record path.


Your location

coarse (network-based) location

Access coarse location sources such as the cellular network database to determine an approximate device location, where available. Malicious applications can use this to determine approximately where you are.


Network communication

full Internet access

Allows an application to create network sockets.


Your personal information

read contact data

Allows an application to read all of the contact (address) data stored on your device. Malicious applications can use this to send your data to other people.

write contact data

Allows an application to modify the contact (address) data stored on your device. Malicious applications can use this to erase or modify your contact data.


Phone calls

read phone state and identity

Allows the application to access the phone features of the device. An application with this permission can determine the phone number and serial number of this phone, whether a call is active, the number that call is connected to and the like.


Storage

modify/delete USB storage contents modify/delete SD card contents

Allows an application to write to the USB storage. Allows an application to write to the SD card.


System tools

disable keylock

Allows an application to disable the keylock and any associated password security. A legitimate example of this is the phone disabling the keylock when receiving an incoming phone call, then re-enabling the keylock when the call is finished.

prevent device from sleeping

Allows an application to prevent the device from going to sleep.

retrieve running applications

Allows application to retrieve information about currently and recently running tasks. May allow malicious applications to discover private information about other applications.

write sync settings

Allows an application to modify the sync settings, such as whether sync is enabled for Contacts.

modify global system settings

Allows an application to modify the system's settings data. Malicious applications can corrupt your system's configuration.




More:


Your accounts

discover known accounts

Allows an application to get the list of accounts known by the device.


Hardware controls

control vibrator

Allows the application to control the vibrator.


Network communication

view Wi-Fi state

Allows an application to view the information about the state of Wi-Fi.

view network state

Allows an application to view the state of all networks.


System tools

read sync settings

Allows an application to read the sync settings, such as whether sync is enabled for Contacts.

read sync statistics

Allows an application to read the sync stats; e.g., the history of syncs that have occurred.


Default

modify secure system settings

Allows an application to modify the system's secure settings data. Not for use by normal applications.
Your accounts - Skype acts as an account authenticator the way Google does; most likely used to easily store your Skype username and password
Your location - probably for statistics and some location-based features
Your personal information - allows you to directly call a contact's phone number, as well as their Skype account, from the contacts application
Phone calls - almost every application needs access to to this section in order to get the phone's unique ID. Skype also needs this to know if the phone is in a call.
Storage - probably to store cached data
System tools - all of these allow Skype to prevent the phone becoming idle during a call, as well as sync contacts


All other permissions should be obvious.