Buying a Tacoma - Have Questions

I'm going to be buying a 2016 Tacoma in April. I've never owned any kind of truck before. Can anyone answer a couple questions for me?

1. What are the differences between the SR and the SR5?
2. How long is the bed in the smaller cab version?
3. What can i expect to pay for a 4x4, smaller cab, 6' bed, with standard options including power windows & doors, bluetooth and backup camera?
4. Is it better to buy a tonneau cover with the new truck, or third-party after purchase?
5. Do dealers usually sell bed extenders? Is this better to buy third party?

 

Have you spoken to a dealer? You should if those are your questions.

It's always cheaper to buy extra parts after the fact.

I'm not sure how you aren't aware of the bed length and trim differences yet you have committed yourself to buying one in 6 weeks.