Archiving old media is a time-consuming process, unfortunately. How many is "several" in your case? If it's more than a dozen or so you will probably run out of time and patience and will want to consider only doing the most precious ones or else paying someone else to do it. Also it may take a bit of experimentation to get the quality right. I asked around my friends and this is a common experience - so much so that I was considering making a business out of it.
If you're considering outsourcing, there are quite a few companies that will do this for you for around $10 per tape. Obviously this can get expensive if you have hundreds of tapes - it's up to you to decide how much your time and the tapes are worth to you. Unless you're willing to trust the post (or a courier) with your tapes, you'll need to find a local company.
A reputable commercial company is likely to get a better result than you would yourself, unless you're the obsessive compulsive type (not unlikely on Slashdot, I guess.)
I'm not a teacher, so I guess this "obvious" solution must have been found impractical for some reason - privacy concerns or too much manpower required?
Life's about deciding what's important (to you), and doing it. If what you want to do is also important to mankind, then you should want to persuade lots of other people to go in the same direction. It seems to me that Megacorp is offering you a great way to do that. They might also help you avoid the common mistakes in the process.
You should check the small print carefully, though. If their direction turns out to be different to yours, you need some way to escape.
Don't worry too much about losing your freedom - if you want lots of people to help you, you inevitably have to put some time and effort into convincing them. You will still achieve much more than by working in isolation. And you can delegate the boring bits if you have money.
Basic information such as name, address, phone number, spouse's name, employer and so on are (usually) publicly available and trivial to find, e.g. from the electoral roll. I can't see any point in hiding them and personally I make no attempt - they're right there on my web page.
Having used online employment agencies, my CV is also pretty much public information and I have put that on my web page as well. I've found at least one permanent job and a contract as a result.
It may still be prudent not to broadcast your birthdate and mother's maiden name because they're unfortunately sometimes used as security questions, but it's barely worth it because they're pretty easy to discover as well. Maybe it just gives a false sense of security, in fact.
It's possibly still worth making some effort to conceal email addresses from spambots, but that battle is pretty much lost as well.
Bank account details are on every cheque you write (and every electronic payment) so any security based on criminals not knowing them is shaky at best. They're not really secret. Credit card numbers (and even the CVV) are pretty easily read by any waiter or shopkeeper.
My point is, a lot of personal information people think is private or obscure isn't really hard to find at all. It's safest to assume it's all known and concentrate on other security measures (encryption, effective passwords...) for the important stuff.
...but how long will any mobile phone technology last? Will you find yourself having to re-do it all every 5 years as phone/carrier makers obsolete what you developed for?
Symbian for one has a compatibility promise that explicitly addresses that problem. The introduction of Platform Security in version 9.0 caused such an (unavoidable) compatibility break that they effectively had to say "never again". As long as you follow the rules (use only the published APIs and rely only on documented behaviour) you should be OK. [Disclaimer: I work for Symbian]