What happens if i wanna buy little coins now? I need to change the coins later? It's not worth to buy it if it will be problem later..

It's going to be a 1:1 swap. There won't be any problem. The dev will provide instructions. Also, the airdrop will be in the new ERC20 tokens, so the swapping of the coins will be worked out before the airdrop is confirmed.
1:1 swaps are generally pretty easy to do, hopefully the devs do it in a way that is efficient! Im excited to see how they do it