You may have better luck finding bunks or a similar arrangement if you look for a class C rather than a class A. Very generally speaking, class A's are frequently designed for a (retired?) couple, while class C's more frequently for a family. That is of course a generalization and not always true, but the trend is there; and it is more pronounced for diesel pusher class A's.
The ACE is not a high-end motorhome by any stretch, but if you get a used one (so any initial manufacturing defects/warranty work has been taken care of) that's been well-cared for and is in good condition, it ought to be reasonably reliable and sound, at least not really worse than any comparable model--nor likely to be much better, for that matter.
The Ford 6.8 V10 engine is a very reliable engine, and runs smoothly. It tends to be high-revving as truck engines go, and probably seems a bit more so than it is since it has two more cylinders than most, but if you let it go it produces sufficient power and will do acceptably well keeping up with traffic on the highways. It does tend to be a bit on the thirsty side. For a gas powered class A motorhome, you don't have a whole lot of engine or chassis options, to put it mildly.
If you do get bunk beds, make sure they are long enough for however tall your daughters are likely to be in a couple years. Many RV bunk beds are pretty short.
