1. Disks do get older and will be less reliable. Especially after a few years of inactivity. You can replace it, and if you fear vertical positions (don't know why, but if) you can always mount it horizontal. there's enough place in a S3200 to drill some holes and mount a disk.
2. Zip drives work OK, but as with all SCSI devices you need hood SCSI cables. If you use old PC printer cables or parallell cables you surely gonna loose data. The cable provided with the zip is ideal, short and high quallity. If you take care a Zip disk is really reliable, but stay away from magnetic fields and use new disks reguarly. I never had problems with my zips (even the drive fell of the table a few times and it still works.) It can take some abuse, but as a general rule, be carefull, although it's a lot more reliable as a normal diskette.
3. Your S3200 won't benefit, as it only can format up to 512MB (I think), all the rest is just wasted space, and JAZ is far more sensitive to problems as Zip. in short, no good for samplers.
4. Syquest, CD-R, HD's, .. You said your S3200 has a build in MO, why not build in a zip drive? (cheaper as an extarnal model.)
5. You can connect your sampler to your PC, no problem. That way you can transfer sampler to and from your Mac. BUT you cannot access Mac disks via the sampler., due to different format.
6. Yes there is a way. Use a prog called AKAI interpreter, wich allows to read and write on akai disks.