96 ford taurus lx 3.0 duratec

My 96 taurus died suddenly.i bought car
200 with problems.ok so im going to tell you
about experiances ive had last couple
months . The last owner said her keys were
lost in house fire and got replacement
keys.several times i had a hard time starting  
car because theft light was flashing it would
die after few seconds i had to put key in pull
it out sometimes that worked and theft light
stop flashing after it start i could hear
clicking sound under the hood in sync with
alarm systemit seemed. Sometimes car
needed to be jumped battery i thought was
bad i got a bigger battery from a friend and
problem went away for about month.then
alk of a sudden again theft light flashing
rapidly and couldnt start car i pull negative
cable off battery for a few mins and it
started then i drive it ten miles do some
shopping and try start it battery dead needs
jump theft flashing again  i get it started
then whille driving on hwy i forgot to
mention water leak right above starter the
car  died tried to start it just made a click. I
bought starter used from wrecking yard and
got different battery now car wont start not
a click sound  nothing lights on dash come
on headlights are working fine theftlight not
flashing.i need recheck to see if everything
tight.could something else like relay or
fuses be the problem? maybe the water was
dripping on starter could have shorted or
caused fuse or relay to blow? What should i
do?