the pill is like 98% safe againt pregnancy if used correctly but it won't protect you against STDs. It isn't recommended that you use it for life but i think you can go on it for 10years or more with out having any problems.
98% safe. won't protect you against sti though.you can be on them for as long as you like but you should try and take breaks.maybe if you go abroad or something,it could be for a month or two even and that'd be ok.