1. The one you linked is the closest thing to a 'computer science' degree, yep. It's just not called that. Check through the modules and make sure that's the kind of thing you want to do.
2. If you're paying yourself I'm pretty sure you pay by the module. You may also be able to get an OUSBA account, which is a credit account where you pay in monthly instalments (but it does charge interest so you'd end up paying more overall).
3. Personally, I've heard nothing but positive comments from my employers. I am almost finished with my BSc (Hons) Computing & IT degree, and I now work mostly with databases and SQL but also some web development. I only got the job a couple of months ago, and it was advertised as a graduate job. Clearly my unfinished OU degree looked good enough for them to hire me, heh.