Can a natural gas furnace be used for radiant floor heat?

I found these tiny blackish-brown worms on my couch cover, what are they?

What are the tiny black flies on the leaves of my potted plants?

What are the tiny scorpion bugs in my mailbox?

What could be the tiny worms on my mattress?

What should I do if I ca not light my gas water heater pilot?

What should I do if I was bitten by a tiny red spider that resulted in my breaking out in hives and it being hard to swallow?

 hvac  opinion