Hi guys, new to the forum so a big hello to everybody. Wondering if anybody could give me a few reviews and opinions on a few lenses.
I've just purchased the canon eos 550D body, and am planning on buying on 2-3 lenses seperate as I wasn't completly convinced with the kit lenses.

I'm planning on wildlife/outdoor/ sport photography mainly, however I do travel allot so would like a lense which is capable of city and portraite shots.

For the wildlide I have read reviews on the 'Tamron AF 70-300mm f/4-5.6 Di LD Macro 1:2 Lens' , Sigma 70-300mm f/4-5.6 DG OS , and Canon EF 70-300mm f/4-5.6 IS USM. I realise the canon has the IS option, which I asume at 200+mm will come in use? The apperture of the 3 lenses is high, what are the limitations from this? Will this restrict me in certain situations and am I write in saying I wont be able to get good shallow depth of field shots? Could one the lenses be used for the city and portraties shotes I also desire.

The second lense i'm looking at is the 50mm f/1.8 by canon. I have read and watched very good reviews on this lense, but is it suitable for a standard lense for my camera, in will it be suitable for the travel and portraite shots desirable? I've read its very useful in low light and gives a very good field depth at that apperutre, which I desire in portraite and city shots.

If I purchased one telephoto and the 50mm, would them two lenses be suitable for the shots I wish to get, or am I missing a 'middle', to say, type lense.

Im releativlely new to photography and apologise if not everything I said is accurate and would be very grateful for any advice and help given.
Lastly, I am a university student so I don't have the biggest bank to pay, at the moment, as you may have realised, but I am willing to save and buy later if I can buy two lenses that will cover both.

Thanks in advance :)