Sunspots have 300 health, or 450 with the level 8 helix. This does not scale with level, although the rate of healing does scale.
At base, a sunspot will heal or damage 2 hp for every 1 hp it drains from itself (this can be seen with Stellar Ritual). This is not improved by scaling or the level 2 left helix. However, most other boosts will increase the effect of the sunspot without increasing the health drain, thus increasing the efficiency.
For some reason, consuming an entire sunspot will heal more hp than expected (something like 660 healing when it should be 600). I’m not sure exactly why this is, but I suspect that the healing and damage always uses full ticks, and ticks one extra time as the sunspot dies.
Kid Ultra’s drones work very differently, as they do not consume their own health to heal. Instead, they expire after either healing a set amount (when using single target drones), or after a 45 second timer (when using AoE drones).