I totally agree with you on the first one:

1. Consistent Signup / OAuth Layer
   It sounds technical, but it isn't. It's already out there, in the form of steemconnect.com, but in my opinion it needs a lot more documentation and a better UI / UX. A consistent signup / OAuth layer will dramatically increase the adoption of this product, because more and more people will start to build applications on top of the STEEM blockchain. And, given the nature of the blockchain, the main difficulty in building on top of it is related to the public / private keys management. SteemConnect streamlines this process to a very high degree, but it still needs more coverage and a bit of polish.

Here is my entry: https://steemit.com/challenge30days/@joejoesky/3-things-that-must-be-done-immediately-to-make-steemit-com-a-better-experience-may-30-days-writing-challenge-day-seven