Need help setting up marlin on my ramps 1.4

Hello.

Im about to get my ramps in the mail. So i want to make sure i get all my research done now.

I have a cartisian style printer. with endstops at max. 150x150 bed
heres the part in the config that confuses me. I see others do this diff and wondering what i have to do to mine.
This is the stock config......

// Travel limits after homing
#define X_MAX_POS 205
#define X_MIN_POS 0
#define Y_MAX_POS 205
#define Y_MIN_POS 0
#define Z_MAX_POS 200
#define Z_MIN_POS 0

#define X_MAX_LENGTH (X_MAX_POS - X_MIN_POS)
#define Y_MAX_LENGTH (Y_MAX_POS - Y_MIN_POS)
#define Z_MAX_LENGTH (Z_MAX_POS - Z_MIN_POS)

What should i be putting in mine?

Also, is home and 0,0 the same thing? or is home center of my bed and 0,0 bottom left?

It is simplest to Home Towards Minimum. But that assumes your limit switches are on that side of the various Axis. You can put the origin anywhere you want. But assuming you can home towards Minimum, it is most straight forward to make the home position 0. (Some people do put (0,0) at the center of the bed and have a plus and minus number for the limits of the X & Y axis)

If you can do what I said up above, you would change:

#define X_MAX_POS 150
#define Y_MAX_POS 150