Network and global rules [Help]

Hello, first of all let me say that i have upgraded from 2.4 to 3.0 and so far I’m happy. I have decided not to start using Defence+ until I figured out the firewall part (since it was reworked i think) (and actually that was a strike of luck since so many people have problems with it). So far so good, I’m liking what I’m seeing in this new version.
Now what I would like to understand is the interaction between network rules and global rules since i have never figured this out well.
Second I would like to know if it is safe (i think it is but better be safe than sorry) to add to “System” and “svchost.exe” the following type of rule (the objective is to allow file sharing and remote desktop connectivity):
Allow IP In From MAC xx-xx-xx-xx-xx-xx To IP Any Where Protocol Is Any.
The last thing is a suggestion, I really like the looks of “View Active Connections” but i would like to see a total of bytes in/out for each program, that is, the total amount of traffic generated by a program, because now you can only see it per connection and once it is closed you don’t know how much traffic the application generated since it was open.

Thanks in advance