That's right, golf tees to plug the vacuum leaks so the engine will idle okay.
Since this is such a massive job, you definitely need to check for leaks before putting everything back together. Once the evaporator is in place and connected, take it to the shop and have them evacuate and see if it holds vacuum for 30 minutes. This will be a worthwhile step and expense given the massive scope of this job.
You deserve at least a nomination for the DIY award of the month.