dominicrajHi dominic
I have had couple of swaps in my career.so i got 2 LOR's from my previous bosses and 1 from my professor.
I believe you can get one from your client or customer if you have good relations with them or you could ask someone senior in your company to do it for you.Or you could 1 more from another professor but i wouldnt suggest this unless you cannot get someone from your company to write.
As for hard copies,yes they will have to write on the company letter head.For the conditional acceptance,you will have to scan the letters and upload them.Once your admission is finalised,only then you would have to send the hard copies.
hope it helps
Do let me knw if you have any further queries
Manoj