Consultation needed regarding exapansion

Hi folks,

I am new to storage arena and here goes a real life scenario for which I seek your remarks:-

A sun sparc system is attached to CX3-20f EMC storage [solaris 10 OS, vxvm version is 3.5]

There is 2 diskgroups made from this external storage, one for database, another for some logs etc..

now it has been proposed that new EMC AX 4-5 will be attached along with it for capacity enancement. Please dont ask me questions like why this is being attached or all, because I am new bee into this field and I will be carrying out this integration [I am not decision maker afterall ]

now my questions are:-

1. can CX3 are AX 4-5 go along? If yes then - do i need to work on any patch level of OS/ volume manager?

2. Suppose we are going to enhace these 2 DGs, then do I really need to destory existing DG? or we can create similar RAID and then can add up new space to existing one[resizing]

3. This is high availability cluster server. can we execute the operation without shutting down the system?

[Incremental back up has been implemented]

Pls share your views on this. Thanks