Stop using “All” “Hot/Active/Top” feeds and go search for actual content communities you want, by browsing the community lists, searching for your interests, or looking at new. Then just go to “Subscribed”.

You could just make a simple duplicate email check with special special handling of gmails + and . behavior, and notify the user if they try to create an account for an already registered email.

I’ve always just copy pasted the URL from the adress bar, much easier and worked every time so far.