I tend to prefer 'howto' or 'how to' rather than 'how-to'. Also, plurals normally don't have a single quote. So I'd write 'howtos'. Alternately this could be rephrased as 'How can I submit a how to?'.
how-to is not really a normal word, and to my knowledge, these kinds of words should have 's instead of s.
No. This is a common mistake. "'s" is for possessive uses. I'd think the examples below are correct:
Many how-tos are outdated and misleading. That how-to's spelling is perfect. Those how-tos' usefullness was thus vindicated.
Kuba