How to calculate AWS IO cost for MySQL DB query & inserts?

I am totally new to AWS and want to use EC2 instance, I have already gone through AWS faqs, pricing and cost calculator. But Apart from storage cost IO cost is not clear to me yet.

In my application I am supposed to have around 30-40 GB of database storage, so I assume following will be IO cost:

• IO cost will be querying the data which users will do during day

• Insert/update around 30-40 GB of data every night.

How can I estimate the cost of the above?

In addition to that, will indexing cost me storage + IO also?

At night I will parse 30-40 GB of XML data and insert (mostly update) tables data, so parsing will add computational cost extra? Though I will have micro instance with 100% cpu utilization.

Can anyone give some insight on this please