Welcome Quioloy,
you pose some very interesting questions - but honestly, everything else than the most basic answers would fill a book (or two). :-) I'll try to give you some pointers nonetheless.
ad 1. Everything you do with a single track will change the overall impression of your mix, to some extent. Mixing is about relations between all involved elements (... actually, the old term "balancing" describes the process much better than the uninspired word "mixing"). Assuming that there is not one piece of music like the other, there are no absolute rules how to achieve a good mix, and likewise no "one-size-fits-all"-solution for single instruments. - As the guy who created about 80% of all Vienna Suite presets and 100% of all MIR Pro and MIRx settings I think I'm allowed to say that even the most elaborate ones can be just "educated guesses" to support your quest for a good mix. It's more or less impossible to make any final settings without hearing the results in their musical and acoustic context.
ad 2. All the talk about dry/wet ratios of reverberation mean nothing without knowing the original "dry" signal, without knowing the way the reverb engine technically works, and without knowing how these techniques are actually implemented*). Ideally these values you quoted can give you a rough idea what the they are meant to achieve ("more reverb", "less reverb"), but they are meaningless without context.
*) ... just to give you an example: MIR Pro indeed "thinks" in dry/wet ratios, as it is meant to be used on individual signals. OTOH, Vienna Suite Convolution Reverb "thinks" in independent dry and wet levels, as it is meant to be mainly used in an Aux-send scheme rather than as an insert in a single channel. Both approaches make perfectly sense, but you can't compare them by means of "ratios" easily.
ad 3. What you read is a nice example of possible misunderstandings due to (certainly well-meant) information on the web without context. :-) It is most likely that closer instruments will seem to sound "drier" than those further away - but that's not necessarily just a function of reverb level (i.e. "dry/wet ratio"). The shape and sound of the so-called "early reflections" as well as the initial delay between the signal and the appearance of the first reflections are at least as important as the actual reverb level.
What's more, different acoustic environments will interact differently with different sources: The string section you wrote about will create a different acoustic reaction than the xylophone in the same room, simply because the sharp, high-frequency-rich transients of the latter will provoke other reflection patterns than a soft, floating cello-theme. - Oh, and of course the results will be different in another room. :-)
(... one of my pet-topics during a mix is to put those d*mned triangles in the back of the orchestra. Without the use of some dirty tricks a triangle will always seem to sit right in front of your nose. ;-) ...)
Kind regards,
/Dietz - Vienna Symphonic Library
