Map Fields for Leads Conversion

Hi, there seems to be high levels of limitations as to which fields can be mapped in the different modules. In Leads it does not allow me to map lead source - why, it's the default field that is in leads and accounts modules. Zoho need to look at this for their next update.

There are fields that could be included in leads that are on the accounts module, the leads in the current format only does part of the job that it could or should do for me personally.

Postal Code doesn't map from lead to accounts even though i have correctly mapped this?