My opinions, in no order what so ever.
First is the GUIs. Sirus's texturing work is nice, and tooltips help a ton, but right now IC2Exp GUIs are rather cluttered. They are tough to navigate and are a bit strange. Something more userFriendly would aid the User Experience tremendously.
How are the GUIs cluttered? If there were, then I'd suggest something similar to the way Binnie did it for Extra Bees and Trees, so that holding shift over a section would explain it, and show where the item you shift clicked on would go. But IMO they're fine, and there's not really any good way to "declutter" them, since everything which is there needs to be.
The current mutliblock trend is helping this
Making multi-blocks for things that don't need it? The coke oven from Railcraft was only a multi-block because there was going to be a different way of getting creosote oil from smelting coal. It was new and different, as nothing else really had multi-blocks. Now it seems many mods do it, when it's really not necessary. IC2's way of small scale multi-blocks like the steam generator are flexible, but most of it could be done remotely if necessary. I think the way IC2 has made small scale multi-blocks in the form of heat and kinetic generators and receivers is suitable and has no need to be drastically changed. And reactors, if a little lead heavy for the amount that is generated, are fine too.
add some compressed air through any series of methods, that can be timed with redstone or automated with minecarts
That's just adding steps because you can. Making it difficult for people just puts them off. When there's a compressor, there is no need for specific timing or fancy over the top automation, because Pnumaticraft does things with air, IC2 just adds it to make the blast furnace a little more exciting. The blast furnace makes one thing, and that is refined iron. Maybe if it was more core to IC2, like if it made plates, then perhaps it could do with something a little more, but it doesn't.
Now if you were to take a different approach, one where there was a website, and under it there were several tabs, you could solve this issue. For instance, you would have an about page, a wiki page, a bugtracker page, and a download page.
http://www.industrial-craft.net/ There you go. Were it not abandoned, and maybe tweaked a little, it seems to fit perfectly with what you describe.
it is honestly a terribly designed forum. Both aesthetically and functionally the IC2 forum is a mess
The IC2 forum is fine. I can't see why it is necessary to mess with something that functionally, fits it's purpose. The mess is caused from having a finished threads section, but it not being used. The issue if you start removing old things, is if someone is still doing something, and suddenly they make a duplicate because it' been taken away. Granted, things like the addons, suggestions and support threads need cleaning, but someone will ask why is this happening, or make a suggestion that is a duplicate of one has been moved. Not to mention the time factor of shifting every over.
Will it go up on Curseforge or other mod distro?
No. Why should we bend down to Curse when we have perfectly good ways of distributing it ourselves? That and we never have, so there is no reason to have a duplicate download link which would need to get updated as well.
Will it be Industrial Craft 3?
When the E-net's finished.
That's my opinion on the matters. I expect some people may have differing ones.