Any objection ....
Can I use ...
What is recommended ...
To the above the answer is yes if you have instrumentation to verify that all pulses are correct width and height otherwise NO.

Mr Karas & Mr.Eric - Yes I think I have to go for ISP.
Would you kindly recommend cheapest chip (Eric from from your range of Atmel,Philips,Maxim)

That is not a complete question, what else do you need e.g. there are LPC chips with 500 bytes of flash and ST chips with 256k.

Also, outside the US (and inside) distributors greediness vary greatly, so in one country Philips may be the cheapest, in another Atmel.

Erik