For your safety and everyone elses you need to wait until fermentation is complete in the primary before bottling. If the fermentation completes in the bottle excessive pressures will develop in the weeks of bottle conditioning. The bottles can explode.
Hydrometer readings are the only way to know when fermentation is complete. Three Specific Gravity readings which are the same over a period of three days means Final Gravity has been reached.
I usually wait two weeks before I take the first SG reading.
I have purchased very few bottles that did not come filled with beer. Any beer bottle that had a pry off cap can be reused. Twist offs will not seal well.
Most beers can finish sweet by adding lactose to the recipe. Lactose is not fully fermentable and is sweet. Final gravity will be higher with the use of lactose, but at the same time fermentation will have been completed.
Here is a link to Palmers old book. You will find answers to a lot of your questions that will come up.
http://www.howtobrew.com/sitemap.html
Happy brewing.
