This was added in build 2111
This can be done by subtracting the errant caret from the selection, there are some details at http://www.sublimetext.com/docs/2/column_selection.html
No problem - it would be a lot more obvious what's going on if the defaults were opened read only
If you place your settings in the User File Settings, then this won't happen.
The defaults are intended as a reference, rather than something that should generally be edited.
This was fixed in 2091.
The SQL grammar file had a degenerate regex that could cause significant slowdowns.
5000 line files are, in general, handled fine. Check what plugins you have installed - several can cause severe slow downs.
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