You can paint directly onto vinyl but the paint won't stick to it very well or for very long.
When removing vinyl paper I peel off the top layer by hand and then attack the bottom layer with a steam wallpaper stripper (borrow one - ask around) - then paint.
Emulsion paint needs something to stick to - a base coat thinned with a little water - 10% say, is wise. The top coat will then adhere well to the walls without cracks or bubbles spoiling things. Too much water in the first coat will make the paint unmanagable - splashes all over the place.
A risk of course is that when you strip back all the paper you may reveal damaged plaster underneath and may feel the need to "make good" which might be a chore.
Your age has nothing to do with doing it properly - if you cut corners it will have to be re-done sooner than you would wish - as your "decorator" has demonstrated.
80% preparation time and 20% finishing is about right.
Good luck...
Peccavi
November 2009
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