IMO, these sd work 'like a VCR' as far as recording and playback. There are models w/ harddrives, VHS players, etc. built in, but to me that's overboard.
Bells and Whistles
The VHS option is not bad, but you most likely already have one you can plug into the inputs of the DVD recorder.
I have a DVD recorder for archiving TiVo shows as opposed to accessing my TiVo from my PC. This is nice because it means I can also archive VHS tapes, camcorder tapes, etc. w/no extra work.
I do have a TV card in my PC so I can do this, but using the DVD recorder is easier.
My motto is: buy what you WILL use and not what you CAN use.
I've bought lots of things that CAN do a lot, but in reality I don't use all the extra features. Not in all cases, but in this case, I say pass on the bells and whistles.
Again, there are models w/ all types of features, but if you buy one that is a DVR, DVD recorder, VCR, TV tuner all in one and one part breaks, it's all broke.
Realize Something About Technology
Remember - this is new technology and will only get better and cheaper. If you buy the top of the line today, it's going to be out of date and/or cheap tomorrow. Test the waters w/ a 'good' model and upgrade when the time is right.
Editing Your Recordings
Chances are - you won't. It's a pain for the most part and usually requires DVD-RAM or DVD-RW discs to do it and they're more expensive. If you have a lot of free time for this, you're a rare person.
I was looking for this type of solution in getting ready for having a baby and I knew I wasn't going to be sifting through and editing hours of video.
If you're really interested in editing, look in to PC options. Pinnacle, ArcSoft, Adobe, etc. - they have good solutions for that.
DVD+R, DVD-R, DVD-RAM, DVD-RW
DVD+R and DVD-R are like VHS and Beta: they're both ok right now, but eventually we'll probably land on one or the other. It seems to be leaning towards DVD-R which tend to be less expensive also.
Many recorders and players do both, but cost more. I say save some money, pick one (probably DVD-R) and move on. If you pick the wrong one, chances are in a couple years you'll be buying a new one anyway. Moreover, you'll probably be able to get a cheap one w/ a built in converter or two trays to duplicate one to the other.
DVD-RAM and DVD-RW are the rewritable types. They're more expensive and for my purposes aren't worth worrying about.
I got the Panasonic DMR-E55K:
It records to DVD-R like a VCR. I don't use it to record live TV so I don't use VCR+, but it has it. Also, it has TimeSlip which lets you watch something while it's recording (start recording "24" at 8pm and start watching it from the begining at 8:20 to speed thru commercials like a TiVo). Again, I don't use this, but it has it.
Plain and simple, it records my TiVo, camcorder, digital camera (RCA cable output), VCR, etc. to DVD - that's what I want it to do and that's what it does. It's easy, creates a good menu w/ thumbnails and my chosen titles, it's a name brand w/ good reviews and was fairly cheap (there was a rebate at the time).
Also, it plays CDs and mp3 CDs w/ a good interface so not only does it replace a CD player, but since you can put so many songs on one CD, it replaces a CD changer.
An interesting trick: If you have a digital camera w/ RCA cable output, you can hook it directly into the dvd recorder and create a quick slide-show dvd. Many cameras even have a slide show function built in! You can use the sound from a music channel, CD, etc.
If you're going gung-ho into all the nitty gritty about DVD recorders, you're either just starting here or haven't bothered to read this far. If you're looking for a good, relatively cheap solution to digitize your tapes, archive TiVo, etc., I recommend the Panasonic DMR-E55K.