You can determine what type of roof membrane you have (TPO or EPDM) by removing the interior vent garnish and inspecting the underside of the roofing material. Take a look at this
Dicor video. It explains it well.
As far as roofing sealant, Dicor self leveling lap sealant in the color of your choice should suffice for both roofing materials above. Be aware that there are two varieties of lap sealant, self-leveling and non-leveling (non-sag). Do not use non sag on horizontal surfaces like a roof.
Also, remember to use at least a 3/4" wide butyl tape underneath the mating flange of the fan assembly. You'll need to thoroughly remove the old lap sealant and butyl tape first, a process that will take up most of your time and take away most of your fingerprints.
The actually installation time of the fan itself is very short.