If its not jailbroken at the moment, and u can out any sim in its factory unlcked (bit obvious but said it just to re-iterate)
If thats the case go thru with the jb bro, all this baseband sh*t, ultrsn0w sh*t u'll b reading will be of no relevance.
Not 100% sure what bootrom is but from memory i've never needed to look into any of that when iv jb'd
Safe.
But which JB do I have to use? Coz I'm hearing all this beta stuff and whatnot.