You are staking, because it says "Staking.". It just takes a really long time until you get a stake, because the network weight is like 5 Billion. It's not as uniformly as on POSwallet, but random, sometimes you will not get anything for 10 days and then 10k ESP at once. But you have to be online for the entire time to not miss your chance.
So, is having a little amount per many transactions better than have a unique transaction with a great amount of coins to have the possibility to stake more times?
It's up to you. The advantage of a service like POSwallet is that you don't have to run your own system 24/7. But, they take a little portion of your stakes for themselves, and you have to trust them. Apart from that, the
average reward is the same, when averaging over a long period of time.
Would that be ESPER2? I have a good amount of these coins, I do not know for sure the price of each one! How much does the unit cost?
Find the price of ESP2 aka ESP here:
http://coinmarketcap.com/currencies/espers/The "old ESP" aka ESP1 is only listed on Yobit, and the price is nonexistent because it is not possible to sell your coins there.