robfix

The following will demonstrate what a newbie I am to the 911. I am going to perform some routine maint. on my new (to me) 78SC. Oil change, gearbox fluid change, pop off valve installation and fix a fuel leak. I have the following questions:
In a tech article on this site (see engine drop made easy) the writer suggests supporting the car on jack stands via the torsion bar tube covers. Is this really safe or is there a better support point?
Next question, can both the engine oil and gear box oil be drained with the car jacked up or does it need to be level in order to properly drain?
last question, I have read some posts where the individual has had a hard time removeing the two plugs on the gearbox, is there anything I can do to make this easier?
Anything else I should be aware of?
Any input is greatly appreciated
Rob