As has been pointed out, the double-spaces are a result of typewriter vs print (hard copy) vs screen. When I was taught typing (electric keyboards, no computers for us!), they taught double-spacing. Then I took a journalism class, and I'm pretty sure they taught us single spacing. Now I really just don't care about spacing, as long as there is at least once space between the period and the next letter. Most of my typing is electronic anymore, so there's no hard rule.
However, if there is no extra line between paragraphs, and the paragraphs are not indented, I will not read it. I've read a few stories like this, and I stop after the first few lines. Books indent, so you know where the end of the paragraph is. Computers often have fixed-width paragraphs, so it's hard to tell where the end of the paragraph is without the indents or extra lines. My mind starts frying, and I have to close the window.
And yes, I remember diagraming sentences. I went to 7 schools in 5 school systems, and I'm sure at least two or three schools still taught it. I don't remember all the fancy terminology for it, though.
As far as text-speak goes, acronyms are fine for me. lol, rofl, bbl, stuff like that I don't mind, since some of it is action, others are acronyms. But I abhor text-speak. CUL8R, RU, stuff like that, I hate with a passion. I once yelled at a coworker for ICQ'ing me with text like that. I told him if he was going to tell me anything, spell it out. Hate it, hate it, hate it.
And I'm sure there's other stuff I missed commenting out on, but I'm done for now.
