The only board I know of is, unfortunately, halfchan /mu/'s /prod/ general which is infested with blogposting, poseurs, cloutchasers, and a retard crab bucket mentality much like /ic/, /agdg/, or really any other hub of 'creativity' on that site. I post there occasionally because I like helping people learn, but more often than not, they're more interested in posturing and dragging each other down than trying to collaborate, or discussing the artistic process itself.
I took the plunge into using a DAW about a year ago with only basic tracker skills and no 'contacts' to ask questions to, I just bought Renoise one day and monkeyed around alone every day for months, trying to 'push the envelope' and do something new each time I booted it up. You can do it too. It sounds harder than it is: if you enjoy making music for yourself - if your motivation for doing so is intrinsic, not extrinsic - the improvement comes much more easily.
There are some decent music theory tutorials on youtube but a lot of musicians hardly bother with theory and just 'feel it out', so to speak. It helps to know, but it's not worth studying or sticking to like a science.
For the sound design side, this http://www.cim.mcgill.ca/~clark/nordmodularbook/nm_book_toc.html
seems overwhelming at first but may come in handy eventually, a very old synthesizer 'cookbook' of sorts.
Best of luck