learn pronunciation first, and learn the script of the new language immediately
Correct, and correct. All native speakers of any language are habituated to produce the sounds and perceive the phonemes of their own language, and NOT to produce the sounds or perceive the phonemes of any other language. Acquiring an understandable accent generally takes good training at the beginning.
For an adult learner, CONSCIOUS awareness of the different phoneme system of the target language is almost surely necessary. For some language combinations, dictionaries with International Phonetic Alphabet pronunciation keys can help a good deal. Better quality language textbooks have a beginning section detailing differences in the sound system from the learner's native language to the target language.
Correct, and correct. All native speakers of any language are habituated to produce the sounds and perceive the phonemes of their own language, and NOT to produce the sounds or perceive the phonemes of any other language. Acquiring an understandable accent generally takes good training at the beginning.