Re: iPhone, eBay, etc. as first word of sentence
I think it would have been jarring five or ten years ago. However, I think we have now become perfectly accustomed to seeing things like "eBay", "iPhone", "iPad", "iTouch", "iPod" etc and we know that the first letter is lower case. If someone who was unaware of the brand saw the word at the beginning of a sentence, they would certainly assume it was an error. I wouldn't go out of my way to avoid it but I see how it can be confusing to people who don't understand the terminology.
Remember - correct capitalisation, punctuation and spacing make posts much easier to read.