installer.exe is only a client installer, SafeWriting is server mod, so if you dont plan running own server with server side mod (SSM), you dont need SSMSafeWriting
You probably enabled DX10 physics, that's why you get those messages
About explosives, there is sv_explosive_removal_time 5000 (sets it to 5000 seconds)
And idk what is spectator handling, so probably you gotta create it yourself