"essential and useful" is correct and usable in written English.
You can use it when you want to describe something as important and beneficial. For example: "This book is essential and useful for preparing for the exam."
Circular economy plays an essential and useful role in China in considering economic and ecological sustainability.
Power Doppler sonography is not necessary for every case in routine clinical practice, but is essential and useful in patients where grey-scale sonography is equivocal.
Therefore, searching for compounds or strategies to decrease bacterial biofilm formation or the antibiotics resistance of the pathogens in biofilms, is very essential and useful for the treatment of biofilm-associated disease.
Subsequently, one of the lead authors of ENCODE admitted that the press conference mislead people by claiming that 80% of our genome was "essential and useful".
If other people can confirm that what you're doing is needed, essential, and useful, then you're more likely to get managerial buy-in.
Putin countered by telling Barbara Walters, in an interview ABC broadcast last night, that the treaty, which keeps the U.S. and Russia defenseless against nuclear attack, was "essential, effective and useful".
From an organisational perspective, clinical preparation is essential and a useful strategy to engage clinicians is the use of a simulation exercise prior to study implementation.
It also gives a good place for an essential solid-based wheel and useful items such as hanging nests and hammocks.
The validation and verification of laboratory methods and procedures before their use in clinical testing is essential for providing a safe and useful service to clinicians and patients.
For example, those proteins eliminated due to non-essentiality to Mtb (AX-List) may contain pairs of proteins that could together be essential and may hence be useful, if targeted concurrently.
Understanding techniques that can be performed by that instrument is essential and it is extremely useful to be able to recall how an instrument can sound when played in a higher register, lower register, muted or pedal-ed...etc...etc
