Suggestions for HDD storage

[Gman_TX]

Currently run 4 - 1TB WD Green drives. Pool consists of 3 drives in ZFS RaidZ1 plus a hot spare. One drive went south and the pool shows to be degraded; the age of the other drives is getting up there as well. Just got a WD Red NAS 3TB drive and am not entirely sure after reading the forums and searching the internet if it's possible to run the existing 3 - 1TB drives in a ZFS RaidZ1and mirror them to the WD 3TB drive [mobo has only 4 SATA ports].

Free Space isn't an issue as of yet, but data safety [redundancy] is important; plus using the larger 3TB drive facilitates an upgrade path down the road. Is it correct to say such a configuration provides protection if:
one or all of the 1TB drives failed, or if the
3TB drive suffered a premature failure, as well as
one of the 1TB drives and the 3 TB drive

Is this possible?

The hot spare wouldn't be an available option until such a time as I reconfigured the pool or upgraded the mobo to include more SATA ports.

If this isn't possible, what are the benefits of the options below?
(1) Simply replacing the fried WD green 1TB with a WD 1TB red vs
(2) getting a second 3TB red to run the two 3TB drives in a mirror and possibly adding a third down the road as a hot spare.
Running the mirror or mirror w/hot spare leaves a free SATA port that I might add a lower cost SSD drive to. Would the performance gain be noticeable with the SSD?

I typically see a max of 50Gb/sec across the network which is used for pictures, streaming music and video [movies, and video footage] to a WIn7WMC and android boxes as well as the occasional backup info/programs from windows.

Thanks.

[ChriZathens]

Regarding your Raid10/50-like question: In zfs , a Raid10 config is not a mirror of stripes, it is a stripe of mirrors. So you cannot create a vdev by striping 2 disks and then mirror them with another vdev; you create two or more mirrored vdevs and then create a stripe out of them.
Also:
Spares are a waste.
Notice I did not call them "Hot" spares, because a drive waiting to manually replace a bad drive is not a hot spare, it is just a spare.
I suggest you create a mirror with 2 3TB disks and continue adding mirrors down the road to increase capacity when needed.
If you can go RaidZ2 from the start, it would be even better, but, frankly, any RaidZ2 configuration with less than 6 drives is a terrible waste of space, IMHO.
Also, your transfer speeds will not increase with faster drives, or SSDs.
Even the slowest 5400rpm drives, in a RaiDZ2 which is not a very fast raid configuration, are perfectly capable of saturating a Gbit NIC.
Your transfer speeds are most likely NIC issue and/or CPU issue.