Changing a field type

Changing a field type

Can I change a field type after it has been created and populated with data for records? I want to change a "number" field to a "string". Seems like a reasonalbe transition go this way. 

Is this possible? 

Thanks, 

Brad

P.s. I have created a couple multi look up fields and it has a max of 2. Is this going to increase? Is there a reason for the limit?