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Groovy, 161 bytes!!!
Yay!! Not in last!!
f={s->a=s.split(/\n/)
b=a.findIndexOf{it.contains('|_')}
d=b-a.findIndexOf{it.contains('_')}
print"$b,${a[b].count('_')+1},$d,${a.size()-b-2},${s.count('O')-1}"}
Ungolfed:
f={String s ->
split = s.split(/\n/)
bottomOfChairBack = split.findInde...