S/H with LECA setup

[KC Kam]

Greetings!

I was planning to try out S/H with one of my stressed + almost rootless brassavola nodosa which is kind of recovering.

1. I would like to ask how high should the recommended reservoir be?
2. Any minimum distance between the orchid based (rhizome/stem) from the water level?
3. The hole size for overflowing water can varies as long as the water can flow out quickly right? I was trying to minimize the hole size so that snail doesnt go in from these holes. I am not sure whether i need to do this.
4. Since semi hydro is wet all the time, any snail or pest problem which i need to take note so that i can think of some prevention?

Please advise.

TQ..TQ