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You can simply send STEEM to your account name. No need to fiddle with addresses.

Not sure how to send STEEM from here, never tried.

Thanks for asking this question!
Why the "deposit" button in my wallet here only allows depositing bitcoin and ethereum doesnt make sense to me.

Steemd.com is the block explorer for now.
https://steemd.com
With this site you can look at your stats.
https://steemd.com/@drei4u
Also look at the Distribution
https://steemd.com/distribution
And Witnesses
https://steemd.com/witnesses

For withdrawing from Bittrex, @cyrano.witness is right.
Just use your Steemit account name. It worked for me.

I hope this was helpful.