2005 Grand Am pontiac se gear stuck on park and key does not turn all the way to off :(..

Ok so i have a 2005 grand am pontiac se and this
has been happening for the past couple of weeks.
Everytime i get in the car and start the car the gear
does not want to shift from park(i had my foot on
the brake pedal all the way to the floor). I had to
literally floor the brake pedal and push that little
button on the side of the gear shift all the way in
(which is sometimes hard to do) in order for me to
shift the gear from park to drive and when i turn off
the car the key can't turn all the way . Sometimes i
wait about 2 minutes to an hr to turn the key all the
way to off ..Pls help and let me know how much
would it cost to fix and let me know what's wrong
with my car pls and thank you..is it something i can
fix on my own?