The wattage will depend on where your temps are given your AC/heating, etc. I may be able to get an 85*F basking spot with a 60w here in Florida, but if it's colder where you live then maybe a 75w+ will do the trick. For me 60 and 75w usually work the best to get a basking spot in the mid to high 80's. And if it's a female then I use a much weaker bulb.
And yea, it's fine if the bulb is a little longer than the cage. It won't hurt it.