Where to split long walls
Basement framing is 100% cosmetic.  I am not sure if it is code yet because I would never worry about the code but all places that I have done basements require 16" or less.  And when I say I don't worry about it is because all basements we do are either 16 or 12 so I have never gone back to see if 24 or 18 is code.  If memory serves me 16 is needed for drywall but 24 for paneling.

Some inspectors make sure that there are two points engagement on both the bottom and top plates every span or 8 feet.  I have had maybe 2 inspectors out of 50 ever care.

In essence almost everything you are worrying about is for framing that is load bearing - for you this does not matter.  

Some things you do need to worry about:


if you are doing a long wall most basement walls bulge.  Start at the bulge or give yourself adequate space.  You do not want any of the framing touching the wall.
bottom plates are PT
put some styrofoam under bottom plates
Lay down a chalk line on the floor for long walls.  
When we are framing basements we build upright.  Mainly because the heights differ and I want my install snug.  We measure floor to joist on each side - one joist over.  Then minus three inches, make our two cut and slide those in snuggly.  Once we have the wall level and our boards are OC at 16 we now have a moveable wall piece that we can make slight adjustments to.  We then do the rest of the verticals OC and nail them in.  We have not attached the bottom or top plates.  We do this for the rest of the wall.  If we need to add some crossers to attach a header do our sections don't bow up then we do.  Once the wall is done then we double check the levelness and alignment.  We then nail the bottom plates in - 3 per section.  We check levelness and alignment again and then attach top plates.


Where to split long walls in basement?  Where ever you want.