I'd like to know how to get rid of that crosshair that interferes with selection; it's so annoying.
Firstly, the 3D cursor doesn't interfere with selection.
By default LMB places the cursor, RMB selects.
The crosshair is the 3D Cursor, it is like a cursor in a text-editor it shows where Blender will put stuff and also where the center of some operations can be set to be performed from, such as scaling, rotating, the pivot point when bending, the depth grease pencil is drawn and a point you can use to snap the selection to.
While it may seem strange at first, when you start using Blender but it becomes an indispensable tool when you get more experienced.
Here is a link to the blender manual describing the 3D cursor. https://www.blender.org/manual/editors/3dview/3d_cursor.html
Here is a quick video that will help you better understand how it works. https://www.youtube.com/watch?v=Nlk28Ex9jVQ
The 3D cursor is one of the most used tools in blender. I can not figure out why you would want to disable it, other than it looks ugly and is interfering with your view port.
In this picture, the view port is cluttered with lamps, empties, bounding boxes, and that ugly 3D cursor! However, you can hide all of this easily.
Simply press N in the 3D view to toggle open a sidebar. In it, locate the display section and check "only render"
Now only your pretty view port preview is showing!
This should be a comment but for visibility I will post as an answer. As pointed out above, this is very useful when modeling. However if you find it getting in your way you can hide it without losing any other viewport markers by zooming out and then left clicking somewhere in a corner of your view, (since this is positioned in 3d space it will stay there respective of where you're located) then focus back your object ShiftC.