OK i am going to embark on a really big project something like facebook scale (of course NOT FB replica ). I had few questions

1. How should one start? Do you start with planning, designing, drawing and make sure everything is on paper before you start coding?

2. What things should i be wary of whilst coding? Tip/tricks to make sure i write code efficiently?

3. One thing i am very weak on is website/db replication. For example if my server goes down, how could I do it so that my backup site kicks in because if server is down then I cant do something like:

Code:
if errror 505 send them to a replica site?
Regarding Database, if the site/db are on one server then if server goes down there is no point really in duplicating database & vice versa?

4. How do I go about making sure my site is fast? apart from making sure queries/code is as efficient as it could be?

5. Should I use OOP or MVC? I actually have done MVC and i think it would be a hassle to have three files.. i would rather just do OOP create classes, create a config file and then each page with some logic (i.e. form submission = check input etc)

6. How do you keep track of your progress, where each page is (i.e for MVC, which of each components/pages are related i.e. user model function, user controller function & view..

if i have left anything else please feel free to add it in..