Hi,
I've not worked on a Samsung S5 before, but I've sucessfully repaired a Lumia 545.
First of all, you have to understand exactly what steps to do, otherwise you will end up in trouble. Take a look:
(disassembly)
(screen separation)
Then, for the temperature setting, around 100°C should do the job. People use heat guns for that kind of repair, so it's not an issue.The LOCA glue is not reusable, whereas the adhesive that bonds the case to the LCD module is.
I really hope it's only a lifted connector (but I doubt it) and you don't have to mess around with the touch screen module, since that module is between the LCD and the glass, furthermore it's glued and will need LOCA Uv glue (as an UV source you can use blacklight lamps). You will realize that separating the LCD from the glass is one of the most difficult repair ever, since it is very easy to damage the LCD module, so document yourself before taking any action.
A tip I've learned at my expanses: be very careful in lifting the screen, since you don't want to go for over 40° from the lcd suface, or you will inevitably dent the lcd, and that operation will take a lot of time.