I find it very very hard completing the objectives which involve using weapons available only through credits (air strike, golden bazooka, homing missile).

I would like to earn a few credits after each battle (maybe just only one per victory). I have to wait until I level up to gain a bunch of credits and I still can fail the kill, so I have to wait to level up again to complete the achievements..

I would like to add that maybe three minutes is a little too short, and 5 minutes for every reinforcement is a looooong time to wait when you have to kill an hour or so... I run out of reinforcements in 15 minutes..
Than

also i like for 1 credits per win and 5 is max per day

Liked the idea of 1 Credit per win and 5 max per day.

Boys, have in mind that people work to keep this online game up, so they need to bill a little money from it, otherwise it won't be that worth to keep it running.

It's difficult to keep everyone happy in a free-to-play game. It's the right balance of fun gameplay with some monetisation features. As Brunu has said, we do need to make a profit from the game, otherwise it simply will not survive!

We're constantly looking at ways to make the game more profitable BUT we also always try to make sure that the monetisation of the game doesn't affect the fun of the game!

Thanks for the comments guys!