What do you mean by switch the powerful weapon?
I am unsure on how to do the tab to see your score. Usually some servers have mods where you type like... /statsme and tells you your information. Not sure if there is a way to make it show every time you tab. But, if the server does have /statsme or some other command you can bind one of you keyboad buttons to automatically open that window.
If the stats requires you to say /statsme then you... go to console, the ~ sign, then you type... bind "key" "say /statsme" where key = what ever keyboard button you want. I think this would be the best way to do this.
There could be programs that keep track of stats but you would risk getting banned because it could be detected as a hack so I wouldn't recommend downloading any programs.