1. Yes, with the sofa.
2. No problems with it. We did have some maintenance issues with the slide out on the diesel pusher we owned for ten years before buying our PC, but these were easily fixed and the benefits to us of having the slide out far out-weighted the "problems."
3 and 4. Yes, we would always choose to have a slide out on any RV we might buy. We learned this the hard way by buying our first two RV's without one. We first thought that just buying a longer unit would fix the lack of space issue and didn't recognize the benefit of a slide out. Our experience of having the option to open up some of the floor space convinces us that the slide out is well worth the extra cost, weight, maintenance , etc. even if one of us were traveling alone.
Bruce and Sharon