Marking SCO's complete based upon the Results of a Pre-Test...

Marking the SCOs as completed based on the results of a pretest is a bit tricky but do-able. You can use global objectives to store the results data, but as I imagine you may find out, global objectives only map to satisfaction status not to completion status. This is an unfortunate design flaw in SCORM (but one that is rectified in SCORM 2004 4th Edition). The way to work around it is to have a "dummy wrapper" around the SCO that you want to be completed and to use a rollup rule to mark it as completed. Something like this

Pretest->SCO
----writes satisfaction to several global objectives based on test results

Module1
--Unit 1 (is visible = true, rollup rule - completed if any satisfied, rollup rule, satisfied if any satisfied, flow=true
-----Unit 1 ->SCO (is visible=false, primary objective reads satisfaction from global objective)
--Unit 2
-----Unit 2 ->SCO

That way, the user will only see "Unit 1" and it will be both completed and satisfied when the global objective is satisfied.

If you want to have a splash screen in the post test there are two options. The easiest would be to code the post test SCO to read the status of a global objective and simply display the splash screen but no content unless the prerequisite completion is met.

The other way would be to do something like:

Post Test
----Splash Screen->SCO - is visible= false, if prereq conditions are met then skipped, required for satisfaction = false, objective measure weight=0, required for completion = false
----Actual Test->SCO - is visible = false, if prerequ conditions are not met then disabled