Some things for you to know:
-1. You can flash your voltaire with the mellanox firmware, I can't remember the switch, but if you pull up the flint manual it will tell you. I've done that with IBM adapters to make them into mellanox adapters. Something like "ignore PSID".
0. I've never used Infiniband on windows 7, but IPoIB is non-bridgeable, so that's probably the issue you're having on windows7. The only way around that is possibly doing a NAT connect using RRAS, but i've not gotten that to work either. (but i'm still a relative newbie to infiniband)
1. MHGH29-XTC I've not heard of using one port and 10Gbe and the other infiniband. But If that's possible, you'll need some sort of adapter to go from CX4-SFP
2. to use SRP, you would need to use the Openfabrics drivers, or a very old copy of the mellanox drivers and I don't know if they even support SRP. (version 3.0)
3. It's not possible to plug a 10Gbe switch into your infiniband switch without some form of bridge, like a BridgeX.
4. I don't know about switches with modules, if such a switch exists, it would be a datacenter product with plug-in modules.
5. Your 9024S does not have a module space in the middle, it's the access panel to swap out the fan.
6. As far as Infiniband targets, I uses ESOS which is linux-based. Why would you need zfs? you're exporting the drives as targets to the initiators and then they format them with nfts. At least with ESOS, you have the option to use a virtual file and export that as a drive, but doing that is slower than just exporting the drive and using blockio.