SRT questions - adding after build, MoBo settings, SSD

[Andy T]

I am in the process of building a new machine based with Asus P8Z68-V Pro. In the interest of budgeting, I am thinking of setting it up with a regular 1 TB HDD and then adding a SSD to be used as a cache later. Would I run into problems and have to reinstall Windows if I go that route?
Would it be simpler to just add SSD during the initial system build? Also, what BIOS settings are needed for P8Z68 to use it in SRT mode?
Also, how does Crucial RealSSD 64gb SATAIII fair for this role?

Thanks!