invoices out of excel

I just started using excel to produce invoices but i am saving each invoice as a seprate file is there a way that i can open a new sheet and the template will copy and increase the invoice number? also i have the auto date on so that i dont have to type it if i do it this way if i have 50 sheets will the date be the same on all of them seeing as the dates of the actual invoices will be different. also is there a way to make an access like form for entering data but printing as if it was templated with my invoice? sorry im ok with all of these programs but by no means an expert