Whether tape backup and/or software (or hardware) RAID are recommended depend largely on the application of your server, but RAID isn't a replacement for a backup. RAID will not solve the problem of "Oh ****, I didn't want to delete that file!", while a backup can. OTOH, recovering from a drive failure with RAID can be a lot quicker than without it (much more so if you have hardware RAID and hot-swap drives). If you're using the server in any kind of critical application, I'd suggest that both would be the safest bet.
Most SCSI tape drives are pretty much plug and play, AFAIK. IDE may not be as well-supported, but support still seems to be pretty good. Which one is "best" depends on a lot of factors, and the best drive is generally not the cheapest one. Some common tape technologies are Travan, DAT/DDS, and DLT. I've had too much trouble with Travan to recommend it to my worst enemy; I might as well have sent the backups to /dev/null (would have saved me a lot of time). DAT is pretty popular and media is cheap, but I've heard some negative things about its reliability as well. From what I've heard, DLT is pretty reliable (FWIW, it's what I'm looking at for my server when I come up with the money for a tape backup).
Major factors to consider for a tape drive would include capacity, speed, reliability, and price.