Open Rockers
You are correct regarding the vent nipple on the crankcase. Leave it vented to open atmosphere. If you want, you can run a short length of fuel line to it and out of your cowl (if enclosed engine) just to keep it from spitting oil all over your firewall. Regarding the nipples on your exhaust, you only need one. I would suggest blocking off the one on the header tube, and use the one on your muffler for tank pressure.
FP