£14K should get you a good standard car, nothing in it between the BT & ST in standard form on the reliability front. A lot depends on how well the car has been looked after. The BT can be better power wise because of the standard turbos size compared to the ST & gives scope for cheap power, but the ST is a better everday car I'd say.

Depends on what you call long periods. Some don't like being left for a week others can go months. Just one of those things I guess. Mine stays on the drive all year round & gets started / driven every week. Not seen a problem like some have that posted on here after being left in the garage over winter.