Basically, you can have lot of stuff "pre-set" in the seed parts. Which saves users from having to do it themselves.
Note In Teamcenter (I think) you MUST start with a seed part.
In native mode, you can use a "blank" seed part (if this option is enabled in customer defaults) which creates a part "from scratch".
Production: NX10.0.3.5 MP16/TC11.2
I'd rather be e-steamed than e-diseaseled
You might be better off contacting your reseller and asking them to give you a 30 day trial of Learning Advantage.
Or possible a trial on another site such as TATA's , Tata technologies is my reseller (VAR).
Most of the questions you posted are not NX specific
Elmhirst Industries, Specializing in Prototype sheet metal stampings and assemblies
Production: NX 18.104.22.168 / Autoform r7 /WorkNC 2018 r2
PC: Rave Cadbeast: Intel(R) i7-4790K CPU @ 4.GHz /32gb ram /NVIDIA Quadro P2000 on Win10 Pro