Hi slickvik,
You are certainly looking in a great direction. As you probably know I think highly of Texas Mattress Makers and they are also one of the members of this site which means that I believe they compete well with the best in the industry in terms of their quality, value, service, and transparency.
The mattress pad you linked would certainly have some effect on the feel and performance of your mattress (which may be helpful or detrimental) and as you suggested I would wait until you have purchased a mattress and slept on it for a bit before deciding on whether to do any fine tuning by adding any additional mattress pads or toppers.
You will need a mattress protector as well for any new mattress and there is more information about the pros and cons of different types of mattress protectors in post #89 here.
Phoenix