Spiny eel community? Questions on set up and species

[Leo1234]

I am thinking of making my 150 gallon (60in X24in X24in) a spiny eel tank. Right now I have a 15in eel that was sold as a tiretrack eel, but I don't know what species it is since I only see its head every so often. It usually hides in the pvc pipe I have for it.

So here are my questions:
1. My gravel is a 3in mix of sand, small and large rounded gravel. Can they bury in this?
2. Any recommendations for low cost hiding spots? Right now I have a 2ft pvc pipe pipe, a 3ft piece of Azalea Driftwood (i think that's the type) I have a plant LED, but most plants don't work. I have had luck with java ferns though
3. Will Other species of spiny eel mix with My current eel if given more hiding spots?
4. can Macrognathus and Mastacembelus mix? I also have a starry night eel in my 33 growout tank.
5. Ways to eel proof my tank? I have a 1/2-1in gap near my filter intake. I'm thinking of adding screening around it. I'm also worried they might lift my glass lid. It feels heavy, but I wouldn't be surprised if they found a way. Should I add something to weigh the lid down?

I might have more questions later. Sorry if there are a lot of questions. I've kept spiny eels before successfully, but I always want second opinions

 

[Leo1234]

One of the species I’m thinking of getting is Mastacembelus alboguttatus. Does anyone keep them? I also am looking for a picture of one since Ive seen different looking eels onoogle listed as this species. One picture looked brown and blue spotted while another looked black like a fire eel, but had blue spots.