Is this mod safe to use?
I mean there must be a reason why it's banned being shared?
I'm also concerned about a trojan or virus infecting my pc.
Pregmod is safe, from a technical perspective (but make sure you get it from gitgud, of course). It's open-source, reviewed regularly, and the dev team has been doing this for years. They're about as trustworthy as a group of completely anonymous deviants can be.
It's prohibited here under General Rule 7 (sexualization of prepubescent characters), not the rules about malicious software. It may or may not be safe in your country from a legal perspective, for content reasons (loli/shota, bestiality, incest, etc, are all included as optional content, and each is illegal in some places).
is there a way to restart the game to start with week one with the same character i have created without having to start over?
I'm not sure what you mean (start over without starting over)? There is a New Game Plus function which lets you start a new arcology with your existing PC and optionally take a few slaves with you.