I have tried a ton of iPad word processing programs, but I keep going back to Pages because of the iCloud synchronization, which now magically keeps all my documents available across my laptop, my iPad, and my phone. Also, Pages has more advanced formatting than most other iPad writing programs. It seems like most want to go in a minimalist direction and deliver text files using Markdown for formatting. I have one like this called IAWriter which works fine if you like to have no distractions and just a blank screen to type into. Many people swear by Byword for their all-syncing text editor. And some people like Notability because you can switch between typing and writing with a stylus or your finger.

I think you set the grammar checker nationality when you choose the language for your iPad. I don't think you can switch languages midstream -- and US and British are two different languages, as well as, I think, 2 different keyboard layouts. The settings for "International" and "Keyboard" are all under the General header in the Settings app. (That's where settings for spelling and grammar checker are too -- under keyboard -- but you've probably found them. )

I share your frustration that we can't upload photos from the iPad.