if you are in the UK try confused.com or comparethemarket, or gocompare, or money supermarket. they are all comparison sites and most have good info on what different terminolgy means.
the basics are:
comprehensive-covers any one/thing you hit, and your car if its crashed, stolen ir vandalised.
Third party fire and theft- covers any one/thing you hit, but only covers your car if its stolen or set fire to
Third party- the most basic form of insurance and the legal minimum required to drive a car, it just covers everyone else, but if anything happens to your car its not covered, many companies dont offer this as they offer third party fire and theft.
most of the stuff on the form is fairly self explanatory. there is the use, theres SDP which is social, domestic and pleasure, which is jsut normal use of your car, but not going to work/school or using it for a business. you can then add commuting if you travel to work/school and also business if you use it for business of your work pays you mileage.
smaller, older cars are cheaper to insure, prices vary alot depending on where you live, and adding more experienced drivers as additional driver often lower the premium