Thank you very much! But how could I know all of these? Or you mean I should start an investigation for every spending address?

It depends on your wallet which addresses are generated.
Blockchain.info standard wallet generates P2PKH i think (Those starting with 1... ).

What do you mean by the amount of in/outputs? Are these bitcoins or bytes?

Whether bitcoins, nor bytes.
Its the amount of inputs your transactions consists of. You can read more here: https://en.bitcoin.it/wiki/Transaction#Input

The Blockchain.info doesn't provide such info.

To get the actual amount of inputs you need a wallet with more functionality. Electrum (https://electrum.org/#home) is suitable.

Could you please provide an example?

In your case (assuming P2PKH), the size of a transaction would roughly be:

Code:

#IN * 180 + #OUT * 34 + 10 +/- #IN

where: #IN = number of inputs, #OUT = number of outputs

With 1 input and 2 outputs your TX would be at about 257 to 259 bytes.