Can Someone be so kind to explain the basics of the lense for example what f/2.8 means and the different characters for example i think i know IS means Image stabalizer?

I've made my mind up and am going to buy the canon 450d, it will be mainly for taking pictures of pets, family around the garden, beach...

not really for close up shots of flowers... but also for pictures of things in the distance as i live right beside the mourne mountains...

what combination of lens would best suit my needs?

budget around Ł500 for the pair...

thanks

Kevin