You can restart your server from RCon, either from HLSW or while in-game.
<quit|exit|restart> in HLSW will restart the server.
rcon <quit|exit|restart> -or-
ulx rcon <quit|exit|restart> will restart the server if you are in-game.
(It should be noted that if you don't have a auto-restarter installed that the above commands will only kill the server, it will not automagically come back up)
!restart <minutes till>
It seems feasible, I'll look into it.
As for having a "on this day of this week restart the server" function, there is already a program that can do that.
GameMon (You will also need
Qstat installed). I use GameMon on my TF2 server and it works quite well.