Your paste appears to be blank, but to answer your second question, you need to set the font in the edit box header separately from the edit box:
Code:
ChatFrame1EditBoxHeader:SetFont("Path\\To\\Font.ttf", 16, "OUTLINE")
For your first question, I've never done anything on double-click, and the client doesn't have a way to specifically detect this, so you would need to implement your own delay (eg. if the same button is clicked twice in X time, treat it as a double click, but if after X time the button has not been clicked again, run the normal click action). From there, you could probably just call the OnClick script from the relevant chat frame's minimize button, or look at Blizzard's code and see which function(s) they actually call when that happens.