Good questions for here:
1. Will those silencer rings work with the buttons I have selected?
The silencer rings are for the Sanwa and Seimitsu buttons, they will not work with the IL or Paradise LED buttons.
2. These buttons have 12V LEDs. I have done some research and it appears that they'll light up at 5V at around 5 mA (according to a post from you guys on Arcade Controls' forum back in 2011, thus I should be ok driving 8 LEDs off of a USB port's power, by the sound of it. There was mention of 5V LED options, but I didn't see such an option on the site anywhere, nor do I know if the 5V LEDs would pose a greater amperage draw than the 12V LEDs driven at 5V. Advice?
The 5 volt option is not currently available on the site because we are working on bundling these in better packaging, that will possibly be only for 12 V. The 5Volt leds are a super bright led, that draws around 30ma, so so 8 leds would be at 240ma, which may be fine if that's all your driving. if needed we can ammend your order, but these leds are about .75 more for each button.
3. Do these buttons come with the 20g switches? There was said to be an option, but I didn't see a drop down for one anywhere. I'd like to keep everything as quiet as possible, so I'm not making everyone in the house crazy while I bash away on the buttons in the living room *grin*. The plan is to order additional 20g switches for the joysticks (Ultimarc Mag-Stik Plus - I really want the 4/8 way switching from the top of the panel).
Yes, this option for some reason was turned off on the website after the upgrade, I will make sure it goes back on today, thank you for letting us know.