It does that so Spammers that make an account just to post ads, at least can't make links, discouraging them a bit.
You will be able to add links when you have 500 rep, I believe.
The buttons don't disappear for me. Did you perhaps already fix them?
Or do you mean after exporting?
I've never liked the browser buttons. I use sprites instead, so I don't know if they have any current quirks.