i noticed that on each cold start she runs at nearly 2000rpm, but only for few seconds, then gradualy drops and stays idling at around 600-700rpm. is that normal?

At a guess if everything else is running fine after it's just the automatic choke keeping the revs high. Does it start and drive fine after, just the 1st early morning start up

yeah thats it, just the cold start, if i leave her idling for minute or two then she runs very smooth

I shouldn't worry about it then mate just keep an eye on it and the revs for any other change. But I think it will be fine :)

are these cars prone to MAF failure?

I think any car is the MAF is so sensitive, but if it was the MAF you would have other rev and idle problems. :) 

I think this is just normal - as Gambit says if the revs start going all over the place and idle becomes erratic then think about chacking the MAF