Don’t get fooled if you find something old, most of the old 701 and older tutorials around the internet are still valid as the core tools for mesh creation are the same. For example you can find almost every tool explained individually for Modo 601 here. Even old 501 default keyboard shortcut list may come in handy.
If you look at Modo tutorials, you may see that some people use scripting quite heavily, but that doesn’t mean you couldn’t still use Modo Indie without them. For example Tor Frick uses a lot of Seneca’s boolean script and while you can’t use the script on Indie, you can use boolean substract macro, which should give similar results. 901 also includes some functionality that was previously provided by those scrips, like for example perfect circle. Scripts may make some tasks faster but they are hardly essential to have to be able to model in Modo Indie. There are also lots of macros for Modo around and they do work on Indie as well + you can make your own as well. You can find bunch of macros from this written tutorial (I can recommend you to read it as well, as it contains nicely put instructions how to deal with your own keyboard shortcuts and pie menus on Modo).
There’s also now a game webinar series going on, provided by The Foundry and streamed on Twitch. Past webinars should appear online soon as well.
Already linked Peter Stammbach channel is a good resource as well. Then there’s Pat Crandley’s tutorials if you want to get started from the very basics of Modo and 3D modeling.
For substance, I think the official Allegorithmic’s youtube channel is one of the best resources for video tutorials on Substance Painter and Substance Designer. Also don’t forget to check out Substance SHARE for hundreds of free substances which you can open in Substance Designer and learn from.
In case you need help on something specific issue, you can join #modo @freenode IRC or Modo + Mari Indie group’s chat on steam.