Would running a distro in a virtual machine before installing to the hard drive give a more accurate idea of how the distro works with your hardware than a live session from DVD?
I assume you are talking about products like VirtualBox and VMWare Workstation Player. The answer is no, because aside from the CPU (partially) and any devices you passthrough, your real hardware isn't accessible to the VM, so its not being tested, virtual hardware is.A virtual machine is software pretending to be hardware.
Some hypervisors (virtual machine programs) provide full virtualization, meaning a 100% virtual environment (eg: PearPC), but these are slow because you are emulating a CPU. The advantage is you can have completely different hardware than the host (computer running the hypervisor). Others like VirtualBox and VMware Workstation Player use partial virtualization (despite refering to themselves as full virtualization. Nobody uses the terms consistently!) to provide mostly virtualized hardware. They don't emulate a CPU though they don't provide full direct acess either. The result is the VM will have the same type of CPU as the host (though not necessarily the same number of cores, or the same features), but otherwise virtual hardware. These types of hypervisors also usually offer drivers (eg: VirtualBox Guest Addons, VMware Tools) to enable more features (eg: Shared clipboards), and provide additional hardware virtualization assistance (eg: improving graphics performance). At this point I consider them paravirtualization not partial virtualization, but most would disagree with that assessment (paravirtualization being a type of virtualization where the guest OS is modified to work), but it doesn't really matter what you call it. Many hypervisors also allow passingthrough some real hardware, typically usb devices, but some expensive hypervisors allow PCI devices (usually aimed at passing through a graphics card to create a production VM).
Keeping down the wear on my system, especially the HDD and the DVD drive
Your harddrive will still recieve wear, because the VM will be storing it's data on your harddrive in a file (or series of files) that act as the VM's virtual harddrive.
I don't have an infinite supply of blank media and money's tight
Same. I usually use DVD-R for a few important operating system discs. I store disc ISOs on my harddrive, rather than burn discs for everything I download. If I want to try one on my real hardware I just burn it temporarily to a DVD+RW or use a flashdrive.