Hi,
I'd like to use both blank Magic Effects from bloodmoon in my mod but I'm not sure if this a good idea for compatibility's sake. Are there any popular plugins that are already using these two effects, other than minor mods such as new summons or missing bound armor parts?

I wouldnt touch them. Theres a small handful of mods which make use of them but I've never seen any that can actually make them work.

If your going down the summon route I have perfected my summon scripts and I am currently Writing a scripting guide on them - mainly because there have been a lot of people I've noticed asking about scripted summons and similar things. So if you can hold back and wait for the guide then it will help otherwise check out my scripted summoning mod for the scripts and go from there.