Low retaining wall with limestone blocks

Some_randomer

So I had old sleepers around a curved flower bed thingy at the front of the house, and I ripped them out as they were rotten. I bought a load of limestone blocks (see pics) and plan to build a low retaining wall approx 1 foot high around the flower bed, so two rows of blocks.

Trouble is I don't have the skills for this so I'm wondering a few things:

- do I need a concrete foundation / base for the retaining wall? If not what should I lay the blocks on?

- do the blocks need to be cemented together, or would some kind of glue do the job?

- will it be easy or difficult to get the blocks level and flush?

- anything else I should be aware of?

Finally if anyone can recommend a good handyman on north side Dublin that might be able to do this I'd be happy to get the details.

Tia