Mrs Bohn
Hi and welcome. We had a 98 Patriot which is not too different from yours.
Camping World doesn't touch our coaches other than fold up chairs and last option in the world.
There was a recall that required a metal plate be installed under the adjustment for your slide. Call Beaver Coach Sales parts, Larry will likely be familiar and possibly have one. Beyond that it sounds like you could use an adjustment on your slide and new seals or at least a repair.
The ants will get in, its what they do. If not through the slide then in the engine compartment or elsewhere. The poison sounds reasonable to me. Just spray the ground around any part that contacts the ground.
Any new coach is frustrating because there is so much to anticipate and learn. Try to be patient and it will get better. We have all been there, some of us twice!
best regards
Keith