  We develop a consistent formalism in order to explore the effects of density
and spin fluctuations on the quasi-particle properties and on the pairing
critical temperature of a trapped Fermi gas on the attractive side of a
Feshbach resonance. We first analyze the quasi-particle properties of a gas due
to interactions far from resonance (effective mass and lifetime, quasi-particle
strength and effective interaction) for the two cases of a spherically
symmetric harmonic trap and of a spherically symmetric infinite potential well.
We then explore the effect of each of these quantities on $T_c$ and point out
the important role played by the discrete level structure.
