TF2 hammer

Before I say anything-Yes I googled alot of this and went to tf2maps.net (Holy hell no one uses the help forum there) and I need to know some things on hammer to finish working on a map.
First off how do I create a timer that refires? Such as if I set a logic_timer to fire 600 seconds into the game, it only fires once and does not reset
Secondly, how do I control the fog in a map to start disabled and then appear after a timer expires?
Thanks

 

I couldn't tell you, but maybe making a thread on the steam workout forum would be helpful. There is quite amount of map makers that talk on there often and making new maps etc.