Tony,
It looks like you've got yourself into a bit of a pickle, and I'm not talking about the copyright thing. You have a vast amount of information, and have chosen the frames method for navigation, and it seems as though you are almost stuck with this method now.
When designing a site, and especially being very large *One* of the most important things to plan is how it is going to be accessed easily by both the surfers and search engines, prior to jumping right in. Most of us have learned this the hard way. I believe your finding this out now.
With a large amount of text information like this, I would most likely have set it up to display dynamically, with search engines in mind. As well, with the use of style sheets, SSI, and a main-category javascript or SSI menu. That way you can change the look and main navigation of 1000 pages or more with editing only a few files. Bread crumb trails are very helpful as well, for example,
Home > Teachers Manuel > Reincarnation
in smaller print at the top of the page. That way, visitors always know where they are, and can easily jump around.
When doing things this way, it is important to have a logo-link or link to your home or site map page in straight HTML form, so that spiders, or visitors without javascript enabled, can easily access your home page and the rest of your information, if they happen to land on one of your interior pages, which will happen with the amount of text you have.
As well you would need a decent HTML site map. The site map could located on your front page, or at least linked to from your front page so that Search engines can fully spider your information. Also with very long pages, it's nice to have a links back to the top of the page. If you chose to re-design this way, you have a lot of work to do, and should get a good search and replace utility for all your current pages.
I'm not sure of your skill level. If you plan to move to a better host, and make use of SSI, Perl, PHP or ASP etc, my opinion is that you've gone to far into development on your free server.
Now that your there, you can still make use of your frames system and still be somewhat search engine friendly. You need to plan your layout so that it is consistent throughout. Don't make your home page in frames, and don't link your categories in new windows. With your main frame set you should make use of the noframes tag. Presently you have nothing but freehost advertising in your noframes tags. And build an HTML a site map. I'm not going to go to far into this because it can get indepth and complex. besides, personally I would go through the work of transforming the information out of frames. For the simple fact that, the further you go with it the more your stuck with it. A few resources,
http://www.websitemedics.com/frames/mainframe.html
http://www.wordsinarow.com/frames.html
http://www.highrankings.com/framedsite.htm (Jill Whalen)
http://www.searchengineguide.com/dale/2003/0224_d1.html
You may want to look a little further too.
Also you had mentioned searchable. Until you get located on a server with some programming, this is a good free service,
http://www.freefind.com/
I think there is a #pages limit on the free version, and believe they have an option to make a site map as well.
Have fun Tony,
Best regards.
Jim