Most programs only need Outgoing Access, and some may not need to access the internet at all.
There is a section about Program Permissions in the McAfee Help (a link for which is in Security Center). It has this to say about Full, Outgoing, and Block :
Allow full access for a program
Some programs require full access to the Internet to function properly.
If a program has restricted access to the Internet, such as Outgoing or Blocked permissions, you can change its permissions to allow full incoming and outgoing Internet access. Examples of programs that require full access include P2P programs, web servers, and email servers.
Allow outgoing access for a program
You can allow a program to have outgoing-only Internet access. Most programs require outgoing-only access, like web browsers and most network applications.
Block access for a program
You can block a program from having incoming and outgoing Internet access. This is an important option for users who want full control of their PCs, allowing access only for the programs they trust, and blocking everything else.
Ensure that blocking a program does not interrupt your network connection or any other program that requires Internet access to function properly. Certain programs, like web browsers, need access to the Internet to function.
Edit : The link above doesn't always want to go to the right place. The section you want, under 'Personal Firewall', is "Managing Internet connections for programs".