Good Day everyone

We have supplier issues, they are over charging on a few items and at the moment we have to go back to old invoices to compare prices on a daily bases, which is very time consuming and labour intensive, does pastel inventory have a function where you can upload price lists from suppliers and immediately see if there are discrepancies?
Also can you set up a product to display on an invoice as one name and works out the manufacturing materials "in the background" enabling stock control to see exactly what needs to be order?
And also can you just buy the inventory as an add on to pastel Xpress 11?
Can you add Invoices per line item from invoices per invoice number or must you add them as invoice totals?
Sorry for all the qeustions but I've been through the Pastel website and can't seem to find enough information.
I would like to find out all this information before spending lots of money on a program that might not even be able to do everything we need.