https://hebrew-academy.org.il/2013/07/18/%D7%A0%D7%99%D7%A7%D7%95%D7%93-%D7%90%D7%95%D7%AA%D7%99%D7%95%D7%AA-%D7%94%D7%A9%D7%99%D7%9E%D7%95%D7%A9/ הַחַם, הֶחָלָב. רק קריינים מדברים ככה...
If only the noun has the definate article and not the adjective the translation uses the verb 'to be'. החלב חם - 'the milk IS hot'. If the article is on both noun and adjective then the adjective describes the noun directly. החלב החם 'the hot milk'. If there isn't a definate article on either noun or adjective, it could be either. חלב חם 'milk is hot' or 'hot milk'. You use the context to determine the meaning.
what is the system for determining which vowel sounds apply to which words. Looking at this prima facie, I'm unable to determine that the vowel takes the 'a' form. I only know by listening to the speaker but my intuition tells me there's an easier way than rote memory for determining vowel sounds. Can anyone advise?
There is no such system. Classical text, such as the Hebrew Bible, as well as modern poetry, use a system called Nikkud which has symbols for vowels that are seperate from the letters. For modern writing, however, you just need to get used to the language. Don't worry, soon enough you'll recognise anough words and develop an intuition about it!
I am learning to read hebrew for sounds not words, there are dots under the letters that symbolize vowels. Once we have learned that part of the torah with vowels we have to memorize without the vowels. it is very hard to not use vowels after you have been taught for 4 years to read with vowels.
I hope that answers your question