The brutal way to eliminate these spaces woul dbe to set @gridGutterWidth, @gridGutterWidth1200 and @gridGutterWidth768 to 0px (in the file web\styles\bootstrap\002-variables.less).
If you want a more selective control of spacing (have the spacing in one row but not in another), I'll need to further investigate the issue.
Regarding the border question, this is what border are. Each element has its own border. If you want overlaps (i.e spaces between elements), I suggest you try margin instead.
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