OpenBOR already optimizes sprites internally. The first option will NOT save memory and may even cost you memory due to the need for more offset declarations. Always use option 2.
Yes, use option 2. If your sprite is in png, its very optimized already and the extra space won't weight too much.
I made a test and I would earn just 20kb for a whole char, it doesn't worths the trouble.
But in .pcx you will have trouble, since its a very unnoptimized file type. Use PNG and with a single axis.
Its tediuous the need to change the axis in every frame, like we do in Mugen.
As a non-natural english "talker", I used wrong words (one more time)
It was more like :
-1 will save a little more space in your mod size less big mod I mean