I was the victim of an apartment fire in Texas.  The Landlord has been
found 100% negligent.  I will be negotiating with their insurer on my
lost contents.  Am I entitled to replacement cost or to depreciated
value on my items?  Also am I due any other damages outside of my lost
possessions?  Is it worth it to hire a lawyer, or is this a pretty cut
and dried property case?

Who found the landlord to be 100% negligent?  The insurance company? 
A claims adjuster?  A court?  Assuming no one is going to contest that
finding, the short answer is that you will get whatever you negotiate
with the claims adjuster.  They will argue for full depreciated value;
you will argue for full replacement cost.  You will likely end up
somewhere in the middle.  If they refuse to arrive at what you feel to
be a correct number to replace your lost and damaged goods, you may
want to engage an attorney to write a letter and place more leverage
on them.  It is far cheaper for them if they settle with you now
instead of your suing the property owner for negligence.  In terms of
your damages, you will likely only be able to recover for the lost and
damaged goods, unless you also suffered personal injury.  Things like
lost time from work, inconvenience, and lost sentimental value are not
proper damages that you can recover.  An exception might be that if
your actual tools of the trade were destroyed; then you might be able
to make an argument for lost income.  If you are a carpenter and all
your tools burned up, then you might have an argument.