Firebelly Toads Fibreglass Safety? Filter and Wood Questions

Hey all, I'm new here, will post an introduction maybe later but a bit rushed now... just got my 2 firebellies back after a year of them being in someone elses care. Here's my current setup.. it's not ideal but I do have plans...
I do have a few questions I've been trying to have answered for a while now...

* Can a Fluval U1 filter blow bubbles while it is on its side? And I can't seem to find any correct sized piping to make a water feature with once its attached to the filter... i assumed it was possibble - am I wrong?

*Also, going to make a fibreglass structure to hold the land areas and get some guppies in there... is there anything I need to look out for when doing this? I mean what paints would be safe? And would it matter, other than aesthetically, if I didn't paint it?

*My final question is I'm going to get some wood but the only places round here just sell reptile wood... I read online that you can seal it by boiling it for a few hours... is this true? If not, how do I make it safe?

Many thanks