The resolution of most webcams is anything between 360p to 4k video. Depending on your budget and the tasks you hope to achieve with your camera you can easily find one that suits you. The most popular being the ones with 720p - 1080p resolution. These are most favorable for online meetings and recording videos for your YouTube channel. If you need higher quality you can get cameras with 4K resolution though they are a bit more costly.
Yes, most webcams have cameras. Most modern webcams have internal microphones that can be used at the same time as the
camera. It is also possible to connect any microphone to your computer and use that instead
All webcams are considerably lightweight and can be carried around along with your laptop and set up to work just as well. Some even have special lenses that adapt to low light to allow the camera to focus on you as brightly as possible.