Mystery flower ID please
Photos a bit blurry with the flash but they should be distinctive enough to ID (I hope...)
Self-seeders from unknown place. Pleasant surprise, I thought they were weeds!
I think you might be right!
Yes, those are antirrhinums, commonly known as snapdragons. They are annuals, so if you want to keep them, you'll need to leave the seedheads on the plants until they are brown and dry, then empty out the seeds. You can sow them straight away or in the spring.