The questions you are asking could fill a book. In fact, at the bike shop in your neighborhood, they will stock several good books that are a good place to start. Go to your local library, and read the past six or eight issues of "Bicycling" and "Cycling Plus". Visit the "Road Bikes" section of the Forum and read the threads on "What bike should I buy?"...there are twenty of those threads every month.
And, visit three or four bike shops in your neighborhood. Tell the staff what your price range is, and look at the bikes that are available. In US dollars, "good" road bikes begin in the $600 to $800 price range. To get a bike that is significantly better, you need to jump up to the $1,200 to $1,400 price range.
A good bike shop can often fix you up with a 1985 to 1995 road bike that is in excellent riding condition for between $200 and $300. A good, high quality, used road bike will ride just as well as a new bike and save you a ton of money.
Unless you have a racing license, do NOT copy what pro riders do. They have skinny, light 23mm tires and bars four inches lower than the saddle for reasons that make sense for racing, but zero sense for someone riding for fitness and recreation.
Someone new to road bikes should be riding on 28mm or 32mm tires and have their bike set-up so that the highest bar of the bars is level with the top of the saddle. That set-up requires getting the largest frame you can stand over flat-footed without any part of the top bar pressing into your crotch. A good bike shop can help you select the correct size of bike and get it set up for the needs of a new, inexperienced rider.