Probably it was asked before, but I can’t find it.
Is it ok if my friends will submit PSD design from his account, and then I’ll code it to HTML template and submit it from my account? He of course will know about it and I will share with him earnings, but, is it ok from TF’s point of view? Or does one design in all forms (like psd template, html template, or WordPress) need to come from one user?
It’s ok. Just he might need to contact support telling them that you agreed on that.
Yep, when you upload theme just tell to the reviewer you have permission to sell that theme here.
Also it would be better if you sell both PSD and coded designs on the same account – this will help you market your files and you’ll both earn more due to earning rates increasing from sales