Tumbler vs. Ultrasonic

[james_bond_007]

I posted a "WTB" ad for a tumbler or ultrasonic cleaner.
I got a lot of PM's saying to "stay away from Ultrasonics".

I've read other forums on this topic and am having trouble sorting out fact from fiction (aka opinions w/o any good reasons).

These range from
"I've never cleaned by brass and never will"
to
"I like real shiny brass, so I buff them with an electric buffer"
to
"Magic chemical formulas"

Being new to reloading, can you "teach me" about tumbling vs. ultrasonics ?

1) give me the pros and cons of tumblers vs. ultrasonics
2) media - Is walnut or corncob media from the pet store "good enough" and substantially cheaper ?
3) Ultrasonic Cleaning solutions - recommendations
4) Does the inside of a case need to be really clean ?
5) If so, does a tumbler clean the inside of cases as well (or good enough) as an ultrasonic?
6) Recommend an item (brand and type) for someone starting into reloading or brands and items to avoid ?

I plan to reload 7.62x51 or 5.56x45 to start out.