Relative sonority of rhotics vs lateral liquids

OK. First some background.
Describing a "semivowel" as
<http://en.wikipedia.org/wiki/Semivowel>
"Semivowels, also known as glides or non-syllabic vowels, are vowels that form
diphthongs with full syllabic vowels. That is, they are vowel-like sounds that
do not form the nucleus of a syllable or mora; they are not the most prominent
part of the syllable. They are normally written by adding the IPA non-
syllabicity mark [  &#815; ] to a vowel letter, but often for simplicity the vowel
letter alone is written."
and defining "approxmant" as
<http://en.wikipedia.org/wiki/Approximant_consonant>
"In the articulation of approximants, articulatory organs produce a narrowing of
the vocal tract, but leave enough space for air to flow without much audible
turbulence. Approximants are therefore more open than fricatives. This class
of sounds includes lateral approximants like [l], as in lip, and approximants like
[j] and [w] in yes and well which correspond closely to vowels and
semivowels."
it's clear that there are approximants which are semivowels -- for instance [j]
and [w] in many languages, [H] in FRENCH or MANDARIN, [M\] in ARRERNTE,
EWE, FIJIAN, TSIMSHIAN, [?\] in Danish -- and, in some languages,
semivowels that aren't approximants -- such as [I_^ Y_^ I\_^ U\_^ m\_^
U_^ e_^ 2_^ @\_^ 8_^ 7_^ o_^ E\_^ 2\_^ @_^ 7\_^ o\_^ E_^ 9_^ 3_^ 3
\_^ V_^ O_^], some of which occur in some dialects of such languages as
Spanish, Romanian, Samoan, non-rhotic English, German, and maybe others.
And of course it's also clear that there are approximants which are not
semivowels: including [B_o] or [P] in HINDI-URDU, NAHUATL, SAAMI, TELUGU;
[r\`] in ARRERNTE, DYIRBAL; [r\] in  WINTU; [P] or [v\] in KHMER,
NORWEGIAN, SINHALESE; [y\] in some dialects of French, Dutch, Norwegian,
Danish, Swedish, Hebrew, German, Danish, Portuguese, Bengali, Armenian; [e\]
or [<\]in some dialects of Arabic.
(Actually I'm not sure whether or not [r\`] counts as a semivowel.)

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Now:

SIL says any approximant which isn't a semivowel is a liquid, and any liquid
which isn't lateral is a rhotic.  (Or, at least, they used to say that; it looks like
the glossary has been changed so that the
words "approximant", "semivowel", "liquid", and "rhotic", are no longer in it.)
<http://www.sil.org/linguistics/GlossaryOfLinguisticTerms/>

I can easily imagine _those_ rhotics are _more_ sonorous than lateral liquids;
they are more vowel-like.  Vowels are voiced (mostly voiced, anyhow) medial
oral (re)son(or)ants (sonants/sonorants/resonants).  "Medial" means "not
lateral".  The non-lateral liquids -- or at least the non-lateral non-semivowel
approximants -- are also voiced medial oral sonants.  They are the most vowel-
like of all non-semivowel consonants.

But lots of rhotics are trills or taps or flaps.

I think trills and taps and flaps are all _less_ sonorous than _any_ approximant,
_including_ lateral liquids.

Actually, if I had a sonority scale like
1. stops and plosives
2. fricatives
3. nasals
4. liquids
5. semivowels
, I'd put taps and flaps at 1.4 and trills at 1.6.  (Both more sonorous than
stops or plosives, both less sonorous than fricatives, taps/flaps slightly less
sonorous than trills.)  (Can the trills be more sonorous than nasals? I don't
think so, in general.)

So; is "It depends on what kind of rhotic" the answer to the question, "Are
rhotics more, or less, sonorant than lateral liquids?"?

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OK, a BTW question.

It's my impression that nearly every rhotic is either at the uvular or the
retroflex PoA, or is articulated in the tap/flap or trill or non-lateral approximant
MoA.  In fact, I'd leave out the "nearly".
Is this correct?
Is every rhotic that's neither uvular nor retroflex, necessarily either a tap/flap
or a trill or a non-lateral approximant?
Is every rhotic that's not a tap/flap nor a trill nor a non-lateral approximant,
necessarily either uvular or retroflex?

And,
is every uvular or retroflex tap/flap or trill or approximant necessarily a rhotic?