[support] Must separate or same node?

[Koestejo (pipit)]

Dear all,

If I create node with cck for home/building and land,
must assign as one node type, or diffrent?
Because they have similar (but not have all) fields.
For example, land doesn't have size  of building etc

Second how to turn off/on, one/several field, based on the content of one field.
 
For example, if status is sell, then enable  several field of selling, and disable several fields of renting.

If rent then disable several field of selling and enable several field of renting,  etc..

If possible not using form api. Any module for that?

Best regards,

Pipit.