I am new to the world of DSLRs but I am looking to dip my toe in the water. I am going to go on a round the world trip in a couple of months and I am toying with the idea of buying a decent camera to take with me. I have a Canon Ixus 65 which, although it's cheap, is actually very good for pocket camera shots but I am concerned that if that's all I take I will be disappointed with the results when I get back.

I have four main questions:
1) Will I notice a significant difference in quality between say a Nikon D3000 and my Canon Ixus? i.e. is it worth taking an SLR over a compact? is the extra kit worth it or will be frustrating as a new user?
2) If I get an SLR which one would provide a good compromise between quality, size, ease of use and budget (bearing in mind my budget is in the lower end of the scale)? I've seen the Nikon D3000 did well in your recent review but as a compete novice is the guide mode any good or is an amount of pre-knowledge needed to use it?
3) What would you recommend as being in the "essential kit bag" for taking an SLR on a long trip i.e. would it be sensible to get spare batteries, uv filters etc?
4) I'm assuming that a lot of my pictures on the trip will be landscapes and scenery, would it be worth buying a wide angle zoom lens (10-20mm) as well as having the kit lens or would the kit lens (18-55mm) give enough depth of field? (I've always been disappointed with the depth of field on a compact camera and I want to get that feeling of being in the picture).

I know that a lot of the my questions will come down to what I plan to do with camera in the future but with so much information on the internet and as there are so many technical terms used in all the reviews I am all at sea!

Thanks very much for your help and any comments welcome.