hey how's it going?

look, i have created my data validation with a list, it is a list of
customers and vendors, but i would like, when i type the first letter, it
shows me all the data that i have with that letter, i hope it is possible,
and i hope also you can help me.

about the validation too, i would like, in my validation drop drown list, i
would like a caracter that says, " add new" so that way when o want to create
a customer or a vendor, it shows me a window or something to create the new
caracter, i do not know if that is possible too.

thank you for all your information granted.