If you only have 10 gallons then just get two. If you're keeping them together then 1 per 5 gallons is nonnegotiable. You do NOT wanna see a fight break out or stress them out unnecessarily. They'll kill each other.
Silk plants are fine. As long as they can hide, they don't care.
My other suggestion to you is cycle the tank ahead of time. They are very messy eaters. Mine spits bloodworm skins out all the time. So, once your tank is cycled, 50% weekly water changes are recommended too.
Lastly, cover your filter intake with a mesh bag, or stockings if they are tiny and never net them and expose them to air. They could puff and if they fill with air it could kill them. Always move them in water.
Here's the site I used when researching Huey