MegaDrum is a MIDI drum trigger similar to Roland TMC-6 but with more functionality. MegaDrum is a DIY non-commercial project.

If you have some basic soldering skills than yes, you certainly can.

MegaDrum8 has 20 inputs: one HiHat controller, one Kick and nine more dual inputs which can be used as 18 single inputs.MegaDrum32 can have either 22 or 32 inputs depending on the type of Analogue board used.

If we agree not to call a few wires and resistors a programmer, than no, you don't need a programmer.

You either power it from a computer through USB or from a +5V power
adapter capable to give 500mA. Many mini usb power adapters will do,
e.g. a power adapter from my I-mate SP5 phone.

Yes, you can. In that case you don't need 6N138N and everything
directly connected to it and to the MIDIIn/Out.1 connector. In the
current MegaDrum32 schematic these are R25-R29 and D1.

No, not without my permission. MegaDrum is for non-commercial use only.

If you bought a Synthex's kit before 22th January 2009, the price of the kit only included charges to cover Synthex's expenses. If you bought it after 22th January 2009, the price of the kit includes a small, 10 Euros, donation to the MegaDrum project.
I have not given a permission to anybody else to sell MegaDrum kits/modules standalone or as a part of another product.

Again, if you bought a Synthex's kit before 22th January 2009, the price of the kit only included charges to cover Synthex's expenses. If you bought it after 22th January 2009, the price of the kit includes a small, 10 Euros, donation to the MegaDrum project. Thanks!

Yes, you can. You don't need a USB MIDI I/O board/option. You will still need to provide +5V to MegaDrum.

Yes. You can use any inductor with a value between 10uH and 1000uH (1mH)

Very much likely. I have my own drawbacks, point me out to the error
and with your help we'll fix it. The important thing is that MegaDrum
works as I designed it to work even if the whole MegaDrum circuit is a
big schematic error:)

MegaDrum doesn't produce any sound by itself. It is a MIDI trigger
device. You need to connect it to a MIDI sound synthesizer/sampler. It
can be a drum machine with MIDI In or better yet it can be connected to
a computer with drum synthesizer/sampler software, e.g. EZDrummer, BFD,
Addictive Drums. Some say this combination puts Roland TD-12/20 to
shade.

Yes, you can use it on any input except a Kick input.

Yes, you can use it on any input except a Kick input. MegaDrum is
velocity sensitive on both head and rim zones. Plus you will get choke
capability on piezo/switch pads.

Yes, it is.

I thought I'd answered it already. Yes, it is velocity sensitive!

Yes, it can. See this and this

Yes, it does. See this

You are using MAX4558 multiplexers without clamping Schottky diodes(bat 85), aren't you? Although MAX4558 has ESD protection,it
doesn't work well when there is overvoltage on inputs and you still
need clamping Schottky diodes. So in reality MAX4558 isn't any better
than a regular 4051 multiplexer.

There is now experimantal support for Positional Sensing. See Miscelenous settings and http://www.megadrum.info/forums/viewtopic.php?f=3&t=1215 for details.

MegaDrum supports both Roland and Yamaha style 3way/3 zones cymbals.

If this a latest version of MegaDrum without an LCD contrast pot than
you need to adjust the LCD contrast from the MegaDrum menu. After MegaDrum is
powered up, press UP/DOWN to adjust it. If this is an older version of
MegaDrum than there is a 10k VR1 in it. You set LCD contrast with it.
The potentiometer, you have, might be a multiturn type so you might
have to make several revolutions to set correct LCD contrast.

Before trying to troubleshoot the problem, swear that all resistors
(measured with a tester), capacitors and an inductor of correct values
and you have no short circuits or breaks. After that tell about the problem on the forum and I'll try to help. I'll be frustrated if it will have turned out to be a short or a break after all.

From experience some samples of PIC18F2550 don't work properly with the USB firmware version from http://www.megadrum.info/content/downloads. Try my alternative USB MIDI firmware for PIC18F2550 from this thread: http://www.megadrum.info/forums/viewtopic.php?f=3&t=268 . Note, that in this case pin26 of PIC18F2550 must be connected to the ground over a 22k-47k resistor.

No they cannot but there is a workaround. See a guide in the Documentation.