VEVOR Stainless Steel Work Table 30 x 24 x 33 Inch, 700 LBS Load Capacity with 4 Wheels, 3 Adjustable Height Levels, Heavy Duty Food Prep Worktable for Commercial Kitchen Restaurant, Silver

Overall height is 34 inches and height without casters is 31 inches.

Here is the link to the manual: https://d2v0huudrf11kh.cloudfront.net/vevor-center-goods/%E5%B7%A5%E4%BD%9C%E5%8F%B0%E5%B8%A6%E8%84%9A%E8%BD%AE2%281%29_1649921032415.pdf.

Sorry, we do not sell additional parts.

Yes, this product can hold up to 700 lbs, which is fully sufficient for your needs.

Yes, you can. This worktable has a total load capacity of 700 LBS (upper shelf 400 LBS, lower shelf 300 LBS). A 20 QT mixer is well within the safe weight range, so you can place and operate the mixer on it.