First off, I want to wish you the best of luck in your venture. I spent the last year trying to open my own brewery, only to have my investor pull out at the last minute.
1) Nano breweries are tough to make a living on. I have a good friend who runs a nano, and his last year's profit was only 30K. He still works his day job, and the profit goes to paying for his server, and his wife helps out as well. He has a 1 bbl system, with 10 1 bbl fermentors. They are undergoing an expansion, but that is on top of the cost of opening this brewery to begin with. My advice, is to go as big as you can. Best profits come from selling pints in a taproom, or from volume.
2) I love a variety of styles, and love to see such in a brewery. Don't limit yourself to one style, but it isn't necessary to follow the mainstream. Most beer drinkers aren't craft beer drinkers, and don't like to deviate too far from their comfort zones. My advice: Cater to both. Have some small batches of the IPAs, honey chocolate coconut coffee porters, hibiscus licorice oaked blonde, and the like, but do keep to your vision of milder English styles to satisfy the masses. It's not about how wild you can get with a brew, it's how well you can sell what you make.
And again, best of luck, I hope you succeed!