the 2222 is not that great for amplification applications, have you tried your other transistors? (look at the datasheets, like the 328 is a PNP, the 549 and 550 are npn)

and loud is depending on the source, some hard nasty square waves though a single transistor amp is going to be brutal, music on the other hand may not be as noticeable.

personally I am not that good with amp's, I just kind of throw crap at it until its to my tastes (in the case of your third circuit), both cap's are electrolytic, c1 blocks DC and depending on what size it is will cut off frequencies, not entirely sure what C2 does but its probably for clarity of some form

the stock sd library is a watered down version of sdfatlib, and you can get that going pretty fast if you use a 74hc4050 for level shifting (dont have an exact number off the top of my head) guess it depends on which SPI speed its set to in the library

avrdude: please define PAGEL and BS2 signals in the configuration file for part ATtiny85

common error that I get every time on a tiny for years, safe to ignore

as far as your led issue, it may be taking so much time at 1mhz to update that it just jumps, were as 8 times the speed it smooths over it

Obviously, the newer versions.  That's why versions exist.  The older versions have bugs and mistakes. 

which have never been fixed (cough header spacing cough)

yes the 5 volt pins connect directly to the arduino hardware, if you apply 5v somewhere it outputs 5 volts, if you input 5 volts it just feeds that branch just like the output of the USB or voltage regulator on the DC jack

if its a stable regulated 5 volt source it will be fine on the 5 volt pins

no, the 32 bitter is not compatible with the 8 bit models in many ways, and if you are a starter I would avoid the due its still in its "kicking and screaming" phase

not really annoying, but it does blend in with your voice quite well

9 volt battery + LED with no resistor? GAH someone is going to do that ...

otherwise good job

just buy it

http://www.flukeonlinestore.com/2103455.html

oh wow delphi, thought I was the only one still using that

anywho, the mega will have a different usb ID do hicky and will almost certain show up as a different com port, likewise if your using a real com port, the mega has 4, make sure your wired into the correct one using the standard voltage and logic converters.

from the factory its running at 1mhz, with no bootloader, with an ISP you can set the clcok and install the bootloader (its physical software that sits at the start of flash just like the bootloader to your PC)

yawn, another noob that is frustrated takes it out on a group of hobbiest nerds on how they are not experts, when they are in fact NOT EXPERTS

well, your over half way to a board ...

that is cause the cap absorbs the reset pulse

the difference is the auto reset that arduino uses, if you are using ISP to program another 328 you dont need it