Dominic I think you're making the task of learning Polish somewhat intimidating. We are both well placed to advise a beginner as both of us are native English speakers who had to learn Polish, though obviously you are far more fluent than I am. However, I think the standard of fluency to which you aspire on the OP's behalf is quite frankly greater than many people achieve in their own native tongue! To address your points in turn:
1) You certainly need a basic vocabulary but I would disagree about 'thousands' of words just to get started. That should consist of the most commonly used verbs, nouns, adverbs and adjectives together with comparatives and superlatives. There are ways of acquiring the everyday language needed to function in the real world. One of the most basic things you should be able to do in a language is to to talk about yourself, tell people who you are, where you come from, where you live, your family, your profession and be able to obtain the same information from them. That alone gives you a lot of words which for which you will find constant uses in other contexts.
2) Grammar is definitely challenging in Polish and I agree with you, there is no getting around the fact that it has to be 'studied'.
3) Reading. Now come on Dominic, really, Lord of the Rings??? With the greatest respect there are plenty of people who couldn't tackle that in English let alone a foreign language, and the length of it! Short texts are the starting point for reading. Magazines are ideal for that as they contain articles of various lengths and ads which are very short. Committing to reading a long and complex text such as Harry Potter is far too much to expect of a learner.
definitely not a Polish-Polish dictionary.
Totally agree. Can't understand the thinking behind the OP's wish to use one.
@jacobmartin. You'll have an advantage if you've already learned a foreign language as it gives you an idea of how to approach acquiring another language. If not, then focus on the four strands of reading, writing, listening and speaking though speaking is definitely the most important no matter how imperfectly you may do it :) Language is about being able to communicate. I manage to communicate adequately in Polish most of the time even though my grammar is not good and I don't have a huge vocabulary but I can give and obtain information from people. For example, just yesterday a lady on the tram asked me for directions to a local school and I understood her and was able to give her the directions. Another time I helped a partially sighted lady with her shopping in the local supermarket. She couldn't read the labels but I could and could relay the information back to her and ask her what she needed. So you see that's what language is about. It's no use at all reading about Bilbo Baggin's 'eleventy- first birthday' but not knowing how to read the ingredients on a food label :))
By the way if you haven't already done so, learn the Polish alphabet asap. As it's a purely phonetic language you will then be able to read and pronounce correctly or even write pretty much any word as spelling is generally totally phonetic with a few exceptions.
I'll tell you a touching little tale. Last year, I saw an old lady who was struggling with a stick and a bag of shopping so I offered to help her and as we were walking along I apologised for my poor Polish and she said to me 'you may not have good Polish but you have a good heart' isn't that lovely! So you see that's what it's about, language is about being able to connect with other human beings. Good luck with it and enjoy your journey.