Welcome to the Geekbench Mac Benchmark Chart.
Putting stuff on top of the Mini isn't a big deal, they don't vent or dissipate a significant amount of heat out the top. You may want to simply stick to a traditional HDD in the Mini. Mac OS X especially had trouble with them. Today I have a little treat for you and hopefully, it will save you a little money in the process, although to be honest if you bought the Hard Disk version of the Late 2014 Mac Mini, you will probably be thinking that the little powerhouse is not really that great. consider upgrading the hard drive to a SSD or adding more RAM. With the new 2014 Mac mini, Apple decided to use dual-core processors in all three models.
