Can I spray paint cinder blocks?

Sure. If using outside usr exterior spray paint. Will peel after a while if water can still in.

Cinder blocks are concrete which is porous. If you want the color to last, use masonry stain

Yes. I have done a couple of projects with spray paint and it was easy and they have held up great. Here are the posts if you want to check it out. https://ourcraftymom.com/make-fun-diy-cinder-block-garden-planters-under-5/ https://ourcraftymom.com/diy-cinder-block-lounger/

You absolutely can! It's concrete so you could even stain it using concrete stain if you wanted.

Yes! Just buy paint that is safe for concrete!