1. Is there a formula for translating mixing times to an approximate
equivalent of hand-kneading time? I've been trying to follow
Hamelman's recipies to the letter, (especially those that use an
Autolyse technique) only without the benefit of a mixer, I'm usually
stabbing in in the dark trying to guess how to keep my dough properly
hydrated and not over-kneaded.

Of course, my results now are often definitely under-kneaded and
developed, and my crumb, as a result, suffers.

2. When using an autolyse stage, what is your bare minimum amount of
incorporation to enable the autolyse to do its job? Either I get
overzealous at this stage and end up with a clumpy, partially-kneaded
ball of dough, or my autolyse seems too dry to actually begin any
gluten development. (And I just had a thought...is it advisable to do
an autolyse at all when kneading by hand?)

Finally:
Next paycheck, I'm investing in a mixer since I want to return to
making bread with some level of consistency. Is there any reason to
get anything fancier than the Kitchenaid Artisan stand mixer that's on
sale just about everywhere right now? I'll primarily use it for bread
and probably for some other pastries, but that's about it.