oil leaks:
you have the good valve covers.
first degrease the engine. take it to a car wash with several cans of degreaser. i have even taken a floor jack to get under it better.
get the reusable valve cover gaskets. trust me, they are worth the money. note that they require very little torque to seal.
remove the valve covers and clean all that up. run a die on all the studs to clean them up to get a better torque on the valve covers.
you have a little oil on your chain boxes. those gaskets are easy to replace.
but clean up the engine to verify where the leaks are.
next oil change remove the pan on the bottom of the engine. note its orientation. replace the gaskets. run a die on the studs here too.
you may be leaking at the oil return tubes. cleaning the engine will reveal where the leaks are from.
no starting:
could be many things. is the gas good. does it have gas in it.
are you getting spark are you getting fuel.
turn the key on. remove the air filter and lift the sensor plate. you should hear a loud squeal coming from the CIS. try to start it after lifting the sensor plate.
there should not be any play in the sensor plate when lifting. you should feel resistance.
slow starting:
clean the battery terminal ends.
clean the cable end where is connects to the body
clean the connection between the body and tranny.
clean the batt connection to the starter.
starter could need a rebuild. go here for my rebuild.
http://forums.pelicanparts.com/porsche-911-technical-forum/631173-solenoid-starter-rebuild-finally.html