Esperanto uses the Latin alphabet (that's the same as English's alphabet), but doesn't use w, x, q, or y, and has a couple other letters with 'hats' on them, like the French do. You can type it using any keyboard, and, if for some reason you can't use the hats (because you're not supporting UTF-8 encoding, *cough*), the official 'workaround' is to use 'h' after the letter, much like you use 'e' after a German vowel to show that it has an umlaut.
Esperanto is as widespread as English, it just doesn't have the same number of speakers...Esperanto is spoken in at least 85 countries and has an estimated 8 million speakers. However, that number may be bigger now, as it's taken from my 1999 edition of "Teach Yourself Esperanto", but really it doesn't matter. It's like asking, "How many people play chess?" - nobody knows, and it doesn't matter.
As to you seeing Esperanto being no different from English as a second language...look at this:
Computer - Computers
Mouse - Mouses
Eight different ways of pronouncing 'ough', 'g' sometimes being 'j', 'j' sometimes being 'y' and 'x' sometimes being 'z' or even 'sh'! Irregularities among dialects (I didn't do anything vs I didn't do nothing), a vocabulary that's swollen rather than rich and it taking a lifetime to master rather than a few months/a year...et cetera. It's just not suitable.
As you can see, English is full of irregularities, weird spellings and grammatical burdens. Esperanto is streamlined, has a vocabulary common to all European languages and no irregular verbs/grammar rules at all. It's the only spoken language of its kind, and is in the Guiness Book of Records as the only language with no irregular verbs. With 16 grammar rules (yep, that's all...versus the countless number of rules in English) and 400 'root words', you can understand and be understood in about 80% of the language. The rest you pick up as you go. I became fluent in a year, practising only an hour a day. It really is that simple.
Oh, and about the French parasite thing - I mentioned the French thinking English to be a parasite language because the English language is associated with American culture. The French are a proud nation and won't tolerate that (they won't use our word "e-mail", for example, as they see it as too American. They'll make up their own word instead. Same goes for MANY techincal terms). Esperanto belongs to no nation, has no cultural bias and is for everybody. That is why they wouldn't see it as a parasite language.