First, we all would suggest you to use 16.04 LTS version. It has great amount of improvements over its predecessors and also very suitable for SSD. (16.04 has default TRIM function for SSDs.)
If you are planning to use RAID10 I would suggest
mdadm tool as an OS based RAID software. It competes very well against hardware RAID, performs better than cheap RAID cards, and is supported very well on Ubuntu. (
mdadm works better than hardware RAID with consumer grade hardware).
RAID10 is a good choice since it gives you fast access times and a copy of your data. It does make a difference when accessing/writing files in large numbers or when working with big files. Improvement in transfer speed can be ~1.5 to 2 times with double the number of disks (but access speed also depends on cached data hence can be confusing to compare that without cleared cache). You can go through this page for detailed benchmarks (raid benchmarks on Ubuntu).
Ubuntu would treat the RAID array as any other drive and its spin down times can be modified by the user. It is suggested to use
noatime parameter in
fstab to prevent spin-down. This is good since spinning down and spinning up reduces the lifetime of the drive considerably. (most server configurations suggest not to play with spin up/down times but just buy drives with low power consumption).
I see no problems with your plan of OS on SSD and RAID10 array for storage. Good luck.
fstab is a file in which the drives which would be mounted automatically during boot are mentioned and several parameters of those drives are controlled there. You can read more about
fstab here fstab at Ubuntu community wiki
Once you create RAID10 array you would list it in the fstab file and then save the file. There you will need to specify
noatime for never spin down function.