Vehicle problems

So when I start my car it revs up to around 2500
rpms, a constant squealing type  noise while
running.. while doing 60mph on the highway my car
is running at 3000-3250rpms and it drop down to
2250-2750rpms and then back to 3000+ rpms and
kicks going into third gear.. any ideas? Any helps is
greatly appreciated due to this being my first car
and me having no knowledge of them. Thanks in
advance to anyone that can help. The vehicle is a
2001 lexus es300