1. All numbers in your contacts list should match ie landline number 12345678 should be the same person whether its 020 12345679 or +91 20 12345678 for landlines and 912345678 should be the same person for +91 912345678 or 0 912345678. If you have Appsupport installed properly this should work by default.

2. This is what I needed and have been messing around with.
a. First dialing a typical landline number 020 12345678 was showing like this on screen 02012345678 ie without the gap. Till the 10th digit it was ok its 020 1234567 but the moment you type the last digit it would become one number 02012345678 without the gap after the std code. FIXED

b. Dialing mobile numbers with 0 first was displaying like (091) 2345678. I wanted it to be 0 912345678. FIXED

c. When you receive a call from a landline the number displays as +91 2012345678. I wanted this to display as +91 20 12345678. FIXED

You need to edit the UIPhoneFormat.plist located in /System/Library/Frameworks/UIKit.framework/PhoneFormats/

I have actually added a lit bit of data which you can too.
This is the original entry for India in this file:

<key>in</key>
<array>
<string>(0##) #######</string>
<string>00 $</string>
<string>+91 ##########</string>
</array>

This is my version for proper display. File attached also. See link below.

<key>in</key>
<array>
<string>(0##) ########</string>
<string>0 9#########</string>
<string>00 $</string>
<string>+91 9#########</string>
<string>+91 ## ########</string>
</array>