Another trick to warming up your chemicals is to get one of those six-pack coolers. Fill to proper level of hot tap water. Put your mixed developer and beaker in it. Stir with the themometer and in only a matter of minutes, it's done. And if the room temperature is significantly different than the developer temperature, you can also use the cooler re-filled to the proper temperature and place your tank in it between agitations to maintain your developer temperature.
One of those thin, 1° glass themometers rock. They are precise and react to temperature immediately. The short, thick cheap ones need time for the heat transfer and don't have a precise graduated scale.
I use the the Photographers' Formulary
TF-4 fixer. Mostly because it's a non-hardening fixer required for use with my main developer PMK Pyro. But it tells you how many rolls of film you can develop per 1000ml mix and I just keep track on a white board of the date of mix and number of rolls and then discard and mix a new batch when I reach the limit of either useful life or volume of film.