SSD's, RAID, and boot drives.

I have done extensive searching but am unable to find exactly what I am looking for.

What I would like to do is use an SSD in RAID1+0, but a few issues come up. AFIAK, TRIM is not supported in RAID1 (seems like it is supported in RAID 0). Because TRIM is not supported, the life expectancy is around 1-2 years? This is too short for me, I was hoping for 4-5 years. So, any experience of the life of SSD in RAID1 without TRIM? Due to the way it works, it seems like all drives will die approx. at the same time. I am not looking to set up an SSD RAID5 for wear purposes.

So, my options turned into SSD as boot, with HDD in RAID1 (maybe even RAID0+1) To increase performance of the SSD and decrease storage usage, is it a good idea for me to move the user profiles and appdata onto the HDD? I have read that this can cause registry issues as well as actually decrease the performance of the system, because those things are accessed frequently and the SSD is obviously faster than the HDD in RAID.

Is there a way to make the HDD a default installation path? Or do I have to do this manually each time? I have thought about making a shortcut to D:/ on my desktop and just choose that, but I am looking for an automatic solution.

Another issue that came up is how does the backup of the SSD + RAID work? Would I need an extra storage unit? Can I use the RAID as backup as well as redundancy? (If so, how do I do either of these things? - Links please)