I did LEJOG in 2007, over 12 days, We stayed in YHAs and B&Bs, which keeps the luggage weight right down compared with camping. I also like a hot shower in the evening, before heading to the pub to carbo load, courtesy of the local ale.
One top tip I would give you on route planning, is to buy a superscale spiral bound Philips atlas. Tear out the pages you need, highlight the route, and then laminate the pages. You then have a lightweight, waterproof map for the whole journey.
The theory about starting at LE is based on the prevailing wind, but you can't rely on it so I wouldn't worry about it. We had headwinds all the way to Scotland.
Cornwall & Devon are by far the hardest part of the route, so if you make it as far as Somerset, you'll be fine. Whatever you do, avoid the dual carriageway part of the A30. It's a motorway in all but name. Dartmoor is beautiful, but a tough climb and very exposed. Some people go via Okehampton & Crediton instead.
The bike I used was a Thorn Audax - ideally suited for this kind of trip as it is lighter than a full blown tourer, but will carry enough luggage if you're not camping. I recommend Ortlieb panniers - tough as old boots.
My daily distances were about 75 miles, I would advise a bit shorter at the beginning and a bit longer once you're into your stride.
As others have said, the CTC LEJOG forum is a great resource. There's some posts from me on there under the same username.