I would budget to buy a second hand bike and then service the forks.
No one ever services DJ forks.
In terms of sizing for the frames, if you can chose a long if you normally ride one, if you can’t then you can adjust the feel of the bike quite dramatically with the stack height and bar height.
Get plastic pedals to start with as it will be easier on the legs.
Having enough cable slack to barspin may feel pretentious but it will save you tearing a line when you inevitably throw the bike.
I had an absolut MAXMAX and I found it a bit hard work to keep the rear wheel lined up.
Chain tugs are pretty much essential