Just to add a few points to what Ian has written:
Where there is multiple parking choices in one spot you will have choose which one to keep otherwise there will be AI stacked on top of each other, I usually keep the largest as that will also be available for smaller aircraft if needed.
I'm not sure the parking P-00 to P-26 etc. need pushback routes, it looks like they may be drive through parking positions, That's also easier to do
Any stray nodes should be removed, Taxidraw does not always pick these up but they do cause a few problems in FG.
I don't put extra off ramp routes in until I get a basic groundnet with pushbacks working, It's one less thing to confuse the issue if there are problems.
Not sure about hold points, I usually put "normal hold points" in as I was told they were going to be implemented, but that was a few years ago and I have not heard anything since so I suppose it's up to personal choice.