Converting Contacts to Leads to Customers (or qualify imported leads)

Converting Contacts to Leads to Customers (or qualify imported leads)

Hello, I am sorry to bother with an apparently simple issue, but I am new to SOHO CRM and I already searched for more than 1 hr but can´t find a solution to my problems. I hope somebody knows the answers.

1) First I imported all of my 5000+ contacts from Outlook to the Zoho CRM contacts and leads section, because unfortunately I don´t know who to import only selected contacts! Is there a way to only import selected outlook contacts. (by the way I was not able to align the field "category"

2) But more frustrating is the fact, that I would like to work on some of the contacts, meaning that I approach them as potential customers, i.e. leads. This is my first question: How can I convert a contact into a lead? Is is possible at all?

3) Alternatively, I tried to import all my 5000+ contacts to the leads section with selected approval as a lead (because not all of them are leads), but then the approval is so difficult. It shows only 50 leads per page at a time (which means I have to scroll 100 pages) and I can neither search for name or company nor select with other criteria. How can I appove selected CRM leads by criteria, industry or company name?

I hope it´s just me who can´t figure it out ;-) Please help! Thanks in advance.