You need to be very very careful preparing rice for keeping.
If you do it, you will need to cool it down very quickly and keep it in the fridge at all times. I would want a fridge thermometer to be sure it was operating below or around 5 c.
The best way to stop it going claggy is to fry the rice for a couple of minutes before adding water, using olive oil. Once cooked cool rapidly by spreading onto baking trays in thin layers, covered with baking parchment.
As rice cools it will solidify, it's the starch content in the rice and apart from constantly keeping it at a low heat, you can do this if you have a rice cooker, then it will always harden.
Just separate the rice with a fork and re-heat. I wouldn't keep in the fridge for longer than 24hrs and I only ever reheat leftover rice once. Unless you are making egg fried rice for which older rice like this is brilliant then cook it fresh, after all it only takes about 15mins to cook and you're not saving that much time by cooking ahead