I’m glad the site could help you and you certainly made a great quality/value choice.
Congratulations on your new mattress
You’re right that a pillow is an important part of a sleeping system and plays a significant role in your upper body alignment as well. There is more information and guidelines for choosing a pillow in the pillow topic here and the other posts and sources of information it links to that may be helpful.
If your mattress doesn’t need any fine tuning or additional padding then I would choose a mattress protector rather than a mattress pad because mattress pads are thicker than protectors and will have a bigger effect on the feel of your mattress.
There is more about the different types of mattress protectors and the pros and cons of each of them and some links to some good sources as well in post #89 here.