Entity Field and Entity Search Questions

I was wondering what does Search Value Replace Pattern actually do and what possible values we can put in there.

In addition, Is there a way to make the default search value be 478 that can be altered because most of our phone orders are local, and it would make taking orders much faster if 478 is default rather than an empty blank. We’re a small fast take-out restaurant.

In the Entity fields, how can I put the value of the search field into a custom entity data besides the default one?

One more question, is there a way to make a custom numberpad in a custom entity screen with Entity Search?

Sorry for the wall of question. I’ve recently started using SambaPOS and loving it. This is much cheaper than our $1500 POS system. I use a Dell Touchscreen computer with a receipt printer and cash drawer which is about $600 and it works great with your system after hours of learning how it works.
Thanks in advance!

Nvm, I found an alternate solution to my POS.
There is a custom number pad on the custom screen. SIlly me.