Yes, you can use an OEM disk to install using a Full Retail Key (or vice-versa) - it's best if the OEM disk is a System Builder one, but a Dell one will work very well. Other OEM disks may require that you install third-party software. If this is a Dell
disk (or other major OEM provider) it may not request the Key during the install, but will install the OEM Key - which will not be able to activate. You will need to change the Key after the install to the one from your Retail license, and then activate that.
Yes, you can use an OEM license on a Mac with bootcamp - but it's not recommended, since the license will expire with the Mac (even if it dies the day after the install). In theory, it's also a breach of the License terms for OEM System Builder
disks to be used on a pre-built system - but MS usually ignores this particular breach
There is no reason why you shouldn't install a Full Retail Licensed product on a Mac - either in Bootcamp, Parallels, or as a replacement for OSX.