Hello Atul
1.Each equipment is created as installbase in CRM .You cannot create installbase in ECC and replicate to CRM.each equipment will downloaded as component under the installbase in CRM by standard.
2. By defalut on eibase will be created for one equipment. if you want to change the hierarchy like on installbase for all the equipments in one sales order/ delivery document . then you can write the logic in BADI CRM_EQUI_LOAD. which will be triggered once equipments are downloaded in CRM .
3.again you have to write the code in BADI CRM_EQUI_LOAD in case of faulty equipment and then replcaement.
Regards
Naresh