Add a Shipping Field etc

Hi

I need to know if this is possible please.

1. To add a Ship next Day button which will update the cart total by £10 ( for all UK customers ) I presume this is done in the same way as the Discount rules I have already applied. So can Next Day be added on the same form as Discount ?

Also can the request below also be accommodated on the same form

2. When my client ships overseas they get a different price each time. Is it possible to add another field to the Cart which says something along the lines of " Add Overseas Payment " where the client could then type in for example £30 and for it to Update the cart total

Or can this be done where we set in a drop down for example

Next day £10
Countries Zone A which will add £20
Countries Zone B which will add £30 to the cart etc etc

I just want the facililty for them to update the Cart price before they check out

Or am I better off just ading a Shipping Field into the form with ADD SHIPPING RATE

And then put a list next to it saying TYPE IN £10 NEXT DAY or add shipping amount advised

This way I would only need one field for Extra Shipping ?

Hope all makes sense

Thanks for your kind help

John