Whether or not 'r' sounds that don't precede a vowel are pronounced is called 'rhoticity'. Some dialects (Most of those from England, Australia, and New Zealand for instance) are non-rhotic and only pronounce 'r' before a vowel. Dialects from Scotland, Ireland, and North America are mostly rhotic and pronounce 'r' whether or not it precedes a vowel. Non-rhotic speakers do change the preceding vowel, usually by lengthening it or combining it with schwa (an 'eh' sound) to form a dipthong.
The 'followed by a vowel' rule can include the next word starting with a vowel: this is called a 'linking r'. Less frequently there is also an 'intrusive r' which is added between vowels that would otherwise blur together. When intrusive r is not used, a glottal stop is used (as in most North American dialects). Whether an intrusive r or glottal stop is used, it's generally not noticed by the speaker or by any speakers who are used to it.
In some British dialects 'a' can also be pronounced in a way that sounds to those unfamiliar with it somewhat like 'ar' when it's at the end of a syllable. There isn't really an 'r', just a vowel you're not used to.
In your example, "premier", "beer", and "car" all get affected by non-rhoticity, "China" and "Obama" are probably examples of unfamiliar vowels that you are mishearing as ending with 'r', and "vodka and" is an example of an intrusive r.