He intended the language to be more easily learnable than existing national languages, not that it be comprehensible with no introduction.
“Natually readable [to a reader knowing a language with Romance roots] without any rules”? I’m not sure that’s possible. The easier a language is to comprehend without training, the closer it would seem to be to one you already know, it would seem to me.
Zamenhof published a basic grammar guide on a sheet of paper, and provided a basic vocabulary list for the beginner. (There was also translated and original literature). It is possible to learn to write the language, with help of a dictionary, from these. I know people who have done it. Following this, there’s a basic written ten-lesson course available by post or over the net, and then other books and learning materials.
Of course, gaining fluency in speaking and hearing it is another matter, and for this you do need other speakers, especially if you were previously effectively monolingual, like me.
It is pretty much phonetic.
Well, isn’t his orthography closer to Polish/Russian/Eastern European than Western European? No surprise, given where he came from. I don’t know about the choice of carets over the consonants, though; I suppose he could have used haceks and been in line with Czech usage. I seem to recall that Janton (there’s that source again–I really have to ask for my book back) mentions that the u-shaped accent (breve?) over the U follows Byelorussian practice. Again, if true, not a surprise.
I’ve seen a lot of older typewritten stuff from this side of the pond with the diacritics written in by hand. Of course, today, with computers and word processors, it’s easier to get diacritics.
There are a number of variant ways to spell it with no diacritics. One version (the ‘h-method’) uses the letter h after the non-diacriticked consonant to indicate the diacriticked consonant: gh = ĝ, and so on for the others. This is what Zamenhof officially reccommended.
The other main method uses an x insted of an h: gx = ĝ. This has the advantage that x is not otherwise a letter in the Esperanto alphabet, and so it avoids certain spelling ambiguities with words that have the letters gh, instead of ĝ, for example. This method spread with the internet and seems now to be the most common.
Me, when I scribble it by hand, I just use straight lines for every diacritic.
Because sol is the root for ‘lonely’ or ‘alone’: sola = alone (adjective); sole = singly (adverb). He tried to avoid having root forms with more than one meaning, and had to make sure that they differed.