Simon is a blind marathoner who sometimes runs with guides and sometimes alone with an iPhone app. I think he also practices just with an app. You can add him as a friend on Facebook and write to him, he will message you back, he's a great guy. Can't think of anyone better to answer your questions.

http://www.bbc.com/news/av/uk-england-south-yorkshire-41823823/blind-marathon-runner-simon-wheatcroft-to-race-unaided

We have two friends who both run races. Glad to put you in touch with one or both of them. They are great guys. Sportable, a non-profit for disabled athletes, makes sports accessible. Below are articles about both of them and Sportable.

http://www.richmond.com/sports/running/monument-ave-10k/visual-impairment-hasn-t-slowed-ukrop-s-monument-avenue-k/article_e506e4d3-2ace-592a-8baf-f17a215e8aeb.html

http://m.nbc12.com/story/27409685/visually-impaired-runner-takes-on-richmond-8k

https://www.sportable.org

Late here, but we would have a men's calf length sock sewn together to make a loop and slide it onto our forearms just before the elbow.

My brother runs full marathons as a blind runner. He trains and runs with a guide who is tied to his wrist with a shoelace that is long enough to give them both autonomy and still allow my brother to feel directional changes. He also wears a fluorescent vest that says blind runner on the back to alert the others around him not to crowd or get between them.