If you see my thread on AVR Connectivity, (http://www.hifivision.com/audio-video-cables/2608-avr-connectivity.html
) you will find answers to most of what you are looking for. In any case let me recap the jist of your answers.
1. Composite, Component, and S-Video are what are called analogue connections. Most DVD Players will have one or more of these. These connection have limited bandwidth. Irrespective of your DVD Player or TV;s capabilities, composite and S-Video will carry only 480i or 576i. They will not carry progressively scanned pictures. Though technically a component can carry 1080P signals, it is very rare to find a DVD Player, an AVR and a TV that ALL support 1080P over component. In most cases the signals will stop at a max of 720P. There are dicsussions of digital component, but it is yet hyperware.
Whichever of these analogue connections you use, you have to carry audio over a digital connection such as co-axial or optical to the AVR to get multichannel audio. If you connect a source through analogue to a TV you will only get a max of two channel audio. Even if the system displays Dolby or DTS, all audio signals will be down sampled to two channels.
To carry full 1080P signals as well as (upto) 7.1 lossless or lossy multichannel audio, currently, HDMI is the only option.