Fastest is amazon. Shipping might be a tad higher than some places, but not by much (maybe 100 or 200 yen). You will most likely receive it on the release date (April 19th).
About ordering from there, on the corner of the page, there is a "Display in English" option, if you click that, things like preorder buttons should be displayed in english. When you actually set up an account, there's also an option on the page to display everything in English. There is an option for international addresses also. When asked for the furigana of your name, you can just put your name in again.
When you have your account set up, you can just go to the "Your Account" section, and it should look like this:
The red circled area is where it asks if you want this page displayed in Japanese. If the rest of the page was in Japanese, that option would be in English, asking if you wanted to display it in English, you'd just have to click there. Also, you can see the "Set Your Ordering Language Preference" option, once you take care of that, any future visits should be in English.
That about sums it up, I guess.
There's nowhere I can't reach.