See here:
http://www.ukba.homeoffice.gov.uk/visas-immigration/partners-families/citizens-settled/fiancee-proposed-cp/
In answering your questions:
1. You can't apply the visa in the U.K.
2. Yes - this is the average. The actual time needed depends on your application.
3. You are not in a situation that you can request expedited processing.
4. If you have been following U.K. immigration law, then yes.
2012-12-11 01:31:11 補充:
In your case, a settlement visa may be better, due to:
a. NHS coverage
b. the time waited.
As soon as your boyfriend meets the requirement, your new born baby will be a British citizen regardless place of birth.