Hi
Make sure your shared storage is inside VMware HCL VMware Compatibility Guide: System Search
As per VMware Product Interoperability Matrixes ESX/ESXi 4.x is compatible with vCenter 5.5, so you can add 4.x hosts to vCenter 5.5.
No need to install vCenter 4.1, just install vCenter 5.5 and add the 4.x hosts & the 2 new hosts to the new vCenter and so you will have 3 hosts in new vCenter.
Is the shared storage accessible by both 4.x host and new 5.5 hosts?
If yes, then you can vMotion from 4.x host to new 5.5 hosts as long as they have same CPU Series, the procedures are described here: vSphere 5.5 Documentation Center - Moving Virtual Machines Using vMotion During an Upgrade
Use this to check the CPU Series: http://www.vmware.com/resources/compatibility/search.php?deviceCategory=cpu
If they are belong to different CPU Series, you can only perform Cold Migration (requires downtime) vSphere 5.5 Documentation Center - Virtual Machine Migration
Cold migration: Moves a powered-off virtual machine to a new host. Optionally, you can relocate configuration and disk files to new storage locations. Cold migration can be used to migrate virtual machines from one datacenter to another.
Please note that VM hardware version 10 is supported only with vSphere Web Client, you cannot make changes to a VM running VM hardware version 10 via vSphere Client.
Per this KB VMware KB: vSphere Data Protection (VDP) FAQ
VDP (Data Protection & Data Recovery with VMware vSphere) is replacing VDR
Q: Is VDP replacing VDR (VMware Data Recovery)?
Yes. VDR is not supported with vSphere 5.1 and higher.
VDR is being deprecated, but will be supported as detailed in the VMware Life Cycle Policies.
If you have existing VDR, you cannot manage this via vCenter 5.1+
VMware KB: Migrating restore points from VMware Data Recovery to vSphere Data Protection
Managing VDR using vCenter Server 5.1/5.5 is not supported.
Direct migration from VDR to VDP 5.5 is not possible.
You must first migrate to VDP 5.1.10, then upgrade VDP 5.1 to VDP 5.5.