I'm sorry I have no information in the nurse-patient ratio. There are programs here for NP but the only place that I know of them practicing is in the VA.
As far as the boards go, it can be taken in Spanish and English - no problem there. Puerto Rico does not endorse any other state's license so your nursing status anywhere else won't matter you still have to pass the PR "revalida". Just about anything official in PR (driver's license, taxes, ect.) will have an English and Spanish version so you should not have a problem there but the primary language is Spanish so it would be extremely helpful for an easier transition.
Everyone is trying to get into VA. It's government so the benefits are great and the pay is to par with that of the states. Otherwise, working for a 'civilian' hospital you'd probably do much more work and get paid much less. You can definitely survive off of what you're getting paid because, in my opinion, many things in PR are cheaper. The one exception that I've found has been groceries; they're so expensive it's ridiculous! Also, it would be better to not live in San Juan because, as with any big city, it's more expensive. Living in the metro area would be cheaper and it's not a bad commute to SJ if that's where you work.
Your options for work are not as limited as you would think. Yes, you need to speak Spanish to communicate with co-workers and patients but most people will not care if you speak "broken" Spanish so long as you can get your point across. I would suggest that if you cannot get a job at the VA that you do look for jobs in San Juan tourist areas. Your English skills could actually serve as an asset to the hospital as there are many tourists that do not speak spanish that need medical attention. Also, because hospitals in PR are JCAHO accredited all doctors must write their notes in English. There are no rules against nurses writing their notes in English so you can if you choose to. That may make nurse-nurse communication a little difficult if they cannot read English though.
If you would like any more info don't hesitate to ask me! I am only a nursing student in PR at the moment but I will try to answer everything to the best of my knowledge and I could ask my mother about more nurse specific questions for you (she's an RN here). Also, if you have any non-nursing questions about PR I'd be happy to answer those too! I was raised in the states to PR parents and moved to PR after high school with really suck-ish Spanish so I understand the fear you may have of coming here with English as a dominant language.
For more information the PR BON website or the 'Colegio de Profesionales de la Enfermeria de Puerto Rico' is www.cpepr.org
For a list of hospitals in PR go to Asociación de Hospitales de PR