Since it's a goldfarming script, the bann rate is rather high and most people suicide this.
I would say 2-4h a day, but I'(m not sure what's considered safe on fresh accounts. Will have to test that
I just stop the whole webwalkerevent with a breakcondition when i have to eat and then eat myself...
Then just start a new webwalk event... ^^
There 50 ways of doing the same thing, whatever works for you is good