To find the oil leak, clean it up good then cover it in talcum powder and see how it looks in the morning. Report back.
For surging, could be a float adjustment or a couple other delivery issues. Stand by for more advice from others on that one. The high RPM thing is common. It sounds like exactly what it is, a thumper with the throttle pegged. Your old twins and fours sound a little less stressed at high RPM. Do check the valves though.
As always, enjoy your new ride and be safe.