Hori RAP V4 Kai Modding?

im new to Arcare sticks in general, had a Hayabusa V4 before, but never used it alot. I felt the Kuro buttons were a bit wobbly.
Now i bought an RAP v4 Kai (i read somewhere thats the same as the jap Version Hayabusa V5, not sure if thats correct), and
im thinking of replacing the buttons for Sanwa ones.
Which Size do i need ? OBSF-24 or OBSF-30? Or are there a better alternative than the Sanwa?

Also, does a custom Balltop fit, for the Stick? I dont want to replace the new stick for now, but a fresher look would be fine.

Any 30mm buttons will work. Sanwa OSBFs are usually the go-to button of choice, but some people like the Gamefinger buttons as well.

And any 35mm balltop will do. Just pick a color you like.

I was going to swap out the Sanwa for some nice Seimitsu buttons and maybe possibly the Hayabusa joystick for a Sanwa JLW joystick.

Thanks. What about the two cables that go into a button, do they have to be connected in a special order?