How to add shipping rates automatically to cart

Hi

I'm new to Opencart (I'm using version 1.4.8!) and I'm finding it great!
However I have a couple of niggly problems I can't seem to work out:

In my store I'm selling small items and quite large bulky items. I want one shipping rate for the small items and another charge for the larger items. I managed to do this through Weight-based Shipping, although I'm not certain this is the right way to do it!

However now, when I tried a test order, I got to a page where there is only 1 method of shipping offered (the right one thankfully!) but customer will have to choose it through a radio button.
Is there any way to automatically put it on the cart, considering it is the only method of shipping available?
Also, the weight of the order shows (I guessed it would, seeing as I'm using weight-based shipping!) but can it be removed from view of the customer's cart?

Thank you very much for any assistance you can give.

Thanks a million Qphoria!

If this is done - will the shipping automatically be chosen (depending on the stores standard country) and apply directly in shopping cart? or will it just skip the shipping step in checkout process?