I have a problem with paint stains. After painting outside walls with Dulux Weather Shield Magnolia, I find drops of paint on the concrete paths. Can you please advise me on how to remove these paint stains, (using water and scrubbing did not work) ?

Your could not remove the paint because it is not meant to come off concrete. Scrubbing will have no effect unless you catch the drops before they dry out. The only stuff I've come across that will remove dried in water based paints is a product specifically designed for that job aptly named OOPS!

It works very well. I used on emulsion splashes etc on door handles, a worktop and a clear varnished wooden floor. I have not seen it in the big DIY outlets yet but it is available in most of the paint speciality shops.

I have foil wrapped kitchen doors. Is it possible to successfully paint them, if so, can you please advise? 

No problem. All you need is paint; probably an oil based gloss, a tin of ESP primer for shiny surfaces, a few cotton cloths and a small tin of Owatrol oil. Shiny or smooth surfaces like the one you describe used to be a no go before magic ESP came along a few years ago. All you need do is wash the doors with something like Sugar soap and rinse. When dry, wipe on your ESP with a clean cotton, lint-free cloth, and taking care to turn the cloth several times during the process. After about ten to fifteen minutes, after it gets a grip, wipe the ESP off the surface gently - this acts as a further cleaner and removes excess film. Now you must wait at least two hours at normal room temperature and then you are ready to apply your paint. I would suggest applying two coats of your gloss with about 15 to 20% or so Owatrol oil mixed in well. The Owatrol will have the effect of making the paint flow out lovely and smooth with no brush marks or streaks and it will also greatly aid paint adhesion on the doors. If you choose a weak hiding colour paint like yellow, red etc, the Owatrol oil will greatly aid your 'hiding power' and possibly save you having to apply another coat.