SSD suggestions needed

What are your needs, budget, etc.?

How much space can you afford?

Readers are most satisfied if they create a Boot Drive, containing only System, Applications, Library, and the hidden Unix files including Paging/Swap, and move all the users files off to another drive. If the boot drive is a particularly fast drive, that is incrementally better. If the Boot Drive is a low-latency SSD, that is incrementally better still.

If you only add an SSD (but do not create a Boot Drive) the difference on boot up is remarkable. But additional speedups are illusive. After a week, you start to ask yourself, "for this I paid all this money? Not worth it!"

ssd drives

You can probably trim the size if you off load some user files, but also 20% free space for Mac OS and add'l free space for "garbage collection"

Any SSD should be fine.

MacPerformance Blog

There is little benefit at all to using software RAID with SSD.

I would consider putting three questions into one thread, polite and there was no need.