Hi, yes, if it was me, I'd put a piece of sellotape sticky side up, spread the ends of the hairs along its length and another piece of tape over the top creating a sellotape & hair sandwich.
I'd then staple that to a piece of paper.
Also remember to take a sample from as near to your face as possible.
Hair there is naturally lighter.
The factory know this and will make the hairpiece match at the front and make it slightly darker to match the back.
A lot of guys have sent samples from the back of their heads and then found the hairpiece to be overall too dark.

Re the crown, I order freestyle and make a crown by styling it.
That way I can have a parting and change sides or have all the hair coming forward from the crown or even have it all swept back.

I originally didn't order a crown just because I never really had one in my natural hair.
Now I order no crown because its just more versatile.
I'd rather have a choice than have a fixed crown that I couldn't alter.
But thats just my experience, so I think its your choice.
But none of us got all our specifications right with our first order and even years later I'm still making changes and modifications.