I would expect the BES to charge a sanction fee, rather than rent a track, which then doesn't make sense for Jerez to do that if it's in financial difficulties.
The standard GP circuit at Aragon is 3.321 miles, with 17 corners. Near as I can tell, it's 3.231 miles, with 14 corners, if you omit that chicane in the backstretch. Aragon has several good, fast corners, and a fair bit of elevation change. It would be nice to have less tarmac run-off, but even with it, just planting some grass between the barriers would make a very noticeable difference in the look of the place.
Here's a basic rundown of the five confirmed circuits:
Monza- 3.600 miles, 13 corners
Silverstone- 3.667 miles, 18 corners
Paul Ricard- 3.750 miles, 15 corners (3.782 mils, 18 corners, with Mistral Chicane)
Spa-Francorchamps- 4.352 miles, 19 corners
Nurburgring- 3.199 miles, 17 corners
So, while Aragon isn't exactly my favorite circuit, it places pretty well among its Spanish counterparts at present, and isn't absurdly long, nor does it have an absurd numbers of corners, relatively speaking.