Yes the warming rack 7641 fits. I have it on mine. But it rusts as fast as the other nickel plated warming racks. I wish there would be a SS version.
As for the coaster wheels you don’t have to use the Weber ones. I have used these. Less than $7 for a pack of two.
Shepherd Hardware 9406 2-Inch Office Chair Caster, Twin Wheel with Brake, 5/16-Inch Stem Diameter, 75lb Load Capacity, 2-Pack
https://www.amazon.com/exec/obidos/ASIN/B001HYY0L8/tvwb-20
And last but not least I am not a big fan of the Uniflasy grates. I used them on one of my flipper grills. Thin rods, large gaps and welded crooked. But I can highly recommend the Qulimetal grates.