Capturing all Excel data when importing

I have just started exploring Zoho CRM, and am trying to import about 190 contacts from an Excel spreadsheet into Leads. The mapping is pretty slick :-) but there are several fields in my Excel file that I am unable to map - Next Step, Next Step Date, Date of Last Call, Call Log (notes on what was discussed during the call). I am assuming the reason I can't do this is because these items are actually Potentials data, not Lead or Contact - is this correct? Is there some way to bring over all the information into Zoho so I don't have to manually enter it? Should I import into Contacts instead of Leads?

Any guidance you can offer would be appreciated - thanks!