No problem at all to declare money and it's free of import duty.
You need to declare it on the form and write on the back what currencies you bring. They ask you to put the amount you bring, but I left that blank as I didn't want everyone to know that. Make sure you know for yourself how much it is, so at customs they will ask you how much it is, what it's for (you can answer whatever you want) and they will take you to an office with a second officer to count your money. You stay with the money all the time and you tell them you knw importing money is for free, tell them you informed at their customs officer/colleague in the embassy of your home country!! As soon as they know you know the drill, no money/fee/bribe will be asked.
Do report it, if not and you get caught, you pay 10% fine and they can also confiscate the money for x days/weeks until they did an investigation. Also take a proof with its money you withdraw from your bank account back home.
As far as I remember, there isn't a max limitation of what you can bring, as long as you declare it. (Last time in 2012 I brought just under 1M with, without any problem).
I have a leaflet about how to import money, in English, somewhere on my laptop. I could send it to you if you DM me your mail (will be end this week as I'm abroad at the moment.
In many countries you also need to declare it when you leave with bigger amounts of money. I did that also, so I had proof of how much money I brought in, as I had customs at the airport back home, counting my money and write the exact amount on the declaration form.
If questions, let me know. ;-)