Desperately seeking solution to mushy sticky rice in Jambalaya, Paella, Peas and Rice

Use a flame tamer to get the lowest possible and well distributed heat source.

Always rinse and soak your rice, always. Talc, impurities and excess starches are found within most raw rice products. Rinse your rice in multiple changes of water, and make sure you drain it well, to ensure you dont introduce more water than you want.
Resting your rice is essential. Once off the heat, the resting period enables the moisture to distribute through the rice.
Again, your rice needs to be cleaned prior to using. I married into a large Chinese family (who mostly use rice cookers) and they all assiduously wash their rice. Thats where I learned to do so. Wasing the rice in fact, eliminates excess starch, its this external starch which causes rice grains to stick together and get mushy. You also need to play with the water volumes added. A process with a proper resting period requires less water.

Don't rinse. I learned long time ago that first you need to heat oil. When really hit add rice and toast lightly.

Don't rinse your rice. Be sure to cover the pot and don't peek, and definitely don't stir it. Just don't! I learned this one the hard way...make sure you r flame is low and the liquid is the correct amount and you will be ok. You can check rice that is cooking by itself in the pot at 20 minutes and then add a little liquid or cook a little longer as necessary. and most important of all, no peeking and no stirring.

try toasting the rice lightly before cooking it.

No! Stop rinsing your rice. Never ever do that. For paella (especially) and jambalaya do not stir while the dish is cooking. Jambalaya should require a long grain rice and paella a short grain (bomba) rice. The type of rice really matters.

Try a converted rice, problem solved.