ALB in mixed drive speed environment

We currently have a PS6210x (10k) and are wanting to add a 4100x (7.2k) into the group for additional storage.  The 6210 is configured as RAID10 and we are probably going to have the 4100 reconfigured to RAID6 per Dell's suggestion.  I have a few questions about ALB in this type of environment:

• I'm assuming a volume will live 100% on one member or the other, and not be spanned across the two, correct?
• Will ALB provide any help in this environment?
• Would it be best to assign volumes to one member or the other by RAID type or leave the RAID type as Automatic?

Any input is appreciated!