Contract: this links the customer to the contract, it is automatically populated if you add a new customer from the contract screen otherwise you need to select this field. Fields like this react as you type so a list of matching contracts is generated to chose from as you type.
Contract reference number: this is the UPRN see Basic Property Data for information about the UPRN.
Lead Source: if you do a lot of advertising, for instance Google AdWords or trade magazines it is useful to track the effectiveness of different ways to attract new customers.
This field has a number of pre-set options but these options are a part of the configuration process and will change for you based on the type of business development activity you undertake. Customers like this would probably be linked to an internal contract, this would suit a Builders' Day Works situation.
Lead Source Other: use this field to describe the source of the lead if you have selected 'Other' in the Lead Source field. For instance you may not have 'Customer Recommendation' as an option so select 'Other' and type this into the Lead Source Other field.
Property Type: select one of the property type options, this can be configured by customers but, as standard, it contains the following options: House, Flat, Bungalow, and Maisonette but it can hold anything you like including Pub, Restaurant, Bar, Public Building, Plant, Open Space or anything that meets your requirements.
Number of Bedrooms: complete this field if bedrooms matter in your context, if they do not then this field can be hidden, re-purposed or new fields can be added in seconds.