hello and welcome to the forums!
thats quite a tricky problem there..
1. bios update -- lets hope the the motherboard manufacturer might have a bios update that supports booting from a usb flash drive.
2. dvd replacement -- laptop dvd drives are somehow "standard" in terms of being replaceable. the replacement does not have to be an exact model, as long as it fits inside the internal frame of the dvd drive slot.
check with the laptop's hardware guide OR parts-and-replacement reference. you should be able to get the dvd drive's model/service/part number. you can search for the part number on Google and find third party laptop parts vendors.
if you can find the laptop's hardware guide, you could try removing the dvd rom. below are pictures of how someone replaced their dvd drive
if you can post the exact brand and model number of your laptop, we can help you search for possible hardware replacement/maintenance manuals, and/or find third party vendors.
its not likely that you would find a circuit diagram for your laptop. but if you are confident with electronics and stuff, maybe you can indeed hard wire the internal cable to a usb external dvd