Water Pump now oil pressure to low WTF

[Jmaze1972]

Hello everyone, I am new here all around .... new to forum new to Porsche ... new to Boxster .... so hello all.... I hate to be the new guy already looking for answers but I have a real problem and worried I already need an engine . I bought a 2007 Boxster base last year 68k on the odo.... now has 83k it's my daily commuter and fun great running car,I don't drive it hard or race it .... a couple weeks ago the water pump started a leak so yesterday I go to replace it. I am somewhat mechanically inclined but Ford and Subaru mostly in knowledge ( I'm a service Advisor) anyways one of my techs and I took on the task. Seemed pretty straightforward . Backed car up on ramps...secured it... removed belt...and water pump bolts ...go under remove rest of bolts and unclamp hoses ... drain coolant... remove and replace pump and then put everything back ... add coolant ...move off ramp and start car to check for leaks... run vehicle seems to take longer than normal to get to temp . Eventually does and thermostat opens and burping begins.... here's where it gets weird and goes bad ... I get low oil pressure warning that goes away when revving Rpms... I shut off car add coolant and resume burping .... put cap on and go for slow drive warning goes out drives as normal heat starts to work temperature goes up and down assuming due to air pockets back home cool down and add coolant... go to start burping again turn on and idle ... idles about 10 mins .. air purging then low oil pressure light again ... I turn car off then back on rev above 1000 rpms light goes out ... and no heat from vents again assume air pocket ... start car again idle and low oil pressure light again with rattle like noises like Tin can rattling .... oh crap ... shut off car immediately... and crap ... turn key once to start to see if problem reoccurred... and starts with metallic knock rattle then starts and idles ok ... I turn off immediately and now I'm worried I killed the engine... what could I have done in the simple task of changing the water pump that caused this?? Where do I look first ?? Am I doomed? Thanks in advance for any help