I been popping corn for donkeys years...no expert though!
I have a pop corn machine, something like £12 from the big electrical stores. But you can get pop corn makers for the microwave, I have not used one. The old way is to put a knob of butter in a heavy based pan, melt it on a high heat then pop the kernels in the pan and put an lid on quick. Keep on high heat until it starts to pop then shake the pan over the heat until all popping stops...this is important otherwise the kernels and pop corn will be lovely and caramelised (burnt)

Not all the kernels will pop. Take the pan of the heat and leave for 30 secs or so other wise you may get a black eye from a kernel that decides to pop when you take the lid off....they always do!
The toffee, preference really. Melt a knob of butter, add sugar and melt to your taste then slowly pour over the pop corn and toss the pop corn to try and get it distributed evenly as possible...or put salt on the pop corn as an alternative.
IT WILL NOT taste like the commercial stuff.....better!
An electric pop corn maker requires no butter, so no oily taste