Yep, kefir is the most simple fermented food I make. It takes very little effort and isn't all that picky about different types of milk either, although I think it does need some fat, so make sure not to use skim etc... (I've even used heavy cream before and it turns out like custard!)
It takes no electricity however the warmer your house the faster it works. On cold days it takes a bit longer, like every two days. If you need a break from making it, just put it into some milk and leave it in the fridge covered. It will be fine for up to a month, in my experience...maybe even longer.
I would get it into some milk asap by now though, if you haven't already.