You should get a book on the subject, preferably one on Russian phonology or phonetics, but many Russian grammars also dedicate considerable space to the phonology alone. Russian has a so-called deep orthography, so you should be aware of the distinction between orthographical- and phonological changes.

Anyway, I will try answering your two primary questions, regarding vowel reduction and consonant changes, respectively.

1. The unstressed vowels most commonly affected by vowel reduction are а and о. It is, however, quite easy to predict the pronunciation of both these vowels, and the rest - it all depends on the environment in which they are found. The most common vowel reduction of а and о is described below.

- Unstressed а and о in initial- or pre-tonic position are both pronounced /ɐ/.
- Unstressed а and о in pre-pre-tonic- or post-tonic position are both pronounced /ə/.

Pre-tonic refers to the syllable before the stressed syllable, pre-pre-tonic to the syllables before the syllable before the stressed syllable, and post-tonic to the syllables after the stressed syllable. Consider the words паром /pɐˈrom/, молодой /məlɐ'doj/ and рано /ˈranə/. And now the vowel reduction of the remaining vowels.

- Unstressed e and э are both pronounced /(j)ɪ/.
- Unstressed я in pre-tonic position is pronounced /(j)ɪ/.
- Unstressed я in post-tonic position is pronounced /(j)ə/.
- Unstressed ю and у are pronounced /jʊ/ and /ʊ/, respectively.
- Unstressed и and ы are pronounced /ɪ/ and /ɨ/, respectively.

Consider the words поле /ˈpoʎə/, этап /ɪˈtap/, язык /jɪˈzɨk/, юла /jʊˈla/ and игра /ɪˈgra/.

2. You mentioned the rule of unvoicing consonants at the end of a word, which is true for б, г, з, д, в and ж. A couple of other pronunciation rules apply to consonants, especially consonant clusters.

- жч, зч and сч are pronounced like щ (= /ɕː/).
- жж and зж are pronounced /ʐː/.
- чн is pronounced /(t)ʃn/.

Voiced consonants followed by unvoiced consonants are pronounced unvoiced altogether, and unvoiced consonants followed by voiced consonants are pronounced voiced altogether. Consider the words загс /zaks/ and также /ˈtaɡʐɪ/.