Soldiers would be given rations of these foods:
-bread -oatmeal -vegetables -jam -rum -salt and pepper -cheese -dried fruit -tobacco -butter/ magarine -chocolate -mustard -tea
Keep in mind that some of these foods were swapped for others, e.g jam could be swapped for dried fruit.
Safer
There is no answer to that question as there were thousands of soldiers in WW1 but don't know how many in trenches. Plus it depends if you ment British soldiers or soldiers as a generally.
Rats.
There was a menagerie of soldiers in the trenches of WW1.
rats and dead bodies
battle of marne
they got and hour to burry there dead
The trenches were in rained-out muddy areas created by the destruction of the landscape
the trenches affected the soldiers during ww1 ww2 by supplying some cover for the soldiers and they were also a living hell because they held water and were often soaked by blood from fallen comrades
Food
More soldiers died of artillery shell explosions than any other cause
there were trenches in ww1 because obviously the soldiers needed somewhere undercover otherwise they would all be shot on the first day. but the trenches cotributed to the stalemate, so they weren't that affective in winning the war.