On the form it says upto 10 working days for the tax, mot, new reg and private plate retained paperwork to come back and upto 20 working days for the V5 (log book) dude i did mine last Fri. It costs £105 for a year..not sure about the cost for 2 years but it says it on the paperwork.
Also that includes the plate transfer fee £80 so you pay f.a when it comes to putting it on your new motor for example. Hope that helps