Help with basement layout
If you want a wet bar, but without jackhammering, you'll need to put the wet bar near the existing sink so you can route the drain through walls. Might want to go to a 2x6 partition wall to leave plenty of room for the DWV pipe.
When you're removing that existing wall, make sure the joists above aren't overspanned. There are tables on the web to tell you how far a joist of a given size can span. You may need to keep the wall, or build a new load-bearing wall mid-span, to keep the floor above from sagging or bouncing.
Think about moisture and flood control. Is the grade pitched away from the house, do you have gutters, how often does the sump pump run in the rain, do you have a battery or water-powered backup sump pump, etc. You may want to put down a flooring underlay that has those little plastic feet to allow water and moisture seepage to flow to the sump pump instead of being pushed through your finish flooring by hydrostatic pressure. You might consider something like Dryloc for the walls, too.
Cheaper and easier to prepare for moisture now, compared to after water has damaged all the hard work you put into finishing the basement.
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