Plugin to support single, multilingual site

I did a search for multilingual wordpress, and got a lot of hits I am struggling to process. I am hoping someone can recommend a short list of plugins to consider. Please note, I an NOT looking for a translator plugin. What I am looking for is a tiny suite of plugins that facilitate not only displaying multilingual content, but authoring it. Or, if a single plugin will support all I want to do, so much the better.

Here is what I want to do, and why. I have decided to learn a few extra languages (French, German, Arabic), and what to support that learning process by authoring content in English and then translating that content into French, German, or Arabic (or whatever other language I decide to try to learn – I am old, so success in learning is not assured). I recognize that some might suggest I try harder to master English before trying to learn another language, as some might say English itself gives me some trouble (even though it is my mother tongue). 😉 But, I intend to try anyway. 😉

What would be ideal, from the authoring perspective, is to divide the client screen into 4, one for the original English content, a second for editing the content in the language I am working on learning, a third for an English-French(German/Arabic) dictionary, and a fourth for a grammar for the language I am trying to learn. The edit window for the language I am trying to learn ought to support writing in that language from a conventional US keyboard (so it ought to have a virtual keyboard, for those scripts comprised of very different letters (such as Greek or Arabic), or pop-up selectors for languages such as French or German, where the difference in script from English resides more in an additional suite of marks that can be applied to vowels, with the editor being smart enough to know when such a pop-up selector would be warranted.

I’d like another plugin that would take a look at whatever metadata I enter in English (eg data used to try do SEO) and offer to let me enter whatever the corresponding metadata ought to be in whatever other language I am trying to use.

Finally, I would like to allow the user to toggle whether he sees the content in his own language only or along with the original English content (and then, either interlineal or side by side). The idea here is to let fully fluent bilingual/multilingual visitors (ideally scholars) to read both my original English content and my attempt to translate it into their mother tongue, and offer suggestions to improve my use or mastery of the language(s) I am trying to acquire.

I am open to suggestions as to how such feedback is best managed, so I can avoid both offensive and useless feedback clutter, and yet acknowledge useful feed back. I also want to be absolutely certain a visitor can not send data that could harm my system (the classic example of which is a SQL injection attack, or a buffer over-run – I don’t know what risks PHP opens up as I program my web applications in Perl, rather than PHP).

Please do not waste time arguing about plugin X is better than plugin Y, but rather focus on what plugin, or set thereof, will support the capabilities I am after; and of these, which have a good reputation.

Thanks

Ted