Welcome! I just posted my thoughts to a similar thread: New to Shapeoko 3 XL- looking for tips/tricks
As far as table, the sturdier the better - its a heavy machine so I would recommend buying/building as tank-like as possible. I built mine like a cabinet shell out of 3/4 ply (pocket-holes and glue) and it works fine, but I might look to reinforce it even further to make it more solid.
Computer, as an IT professional I can say as long as you are not doing in-depth 3D CAD/CAM work any old PC should be fine. Start with whatever laptop/PC you have and if its not working for you upgrade. I use my Microsoft Surface Pro and love the portability of it.
More so than anything, I would say stick with it - you will fail but from each failure will come a piece of valuable knowledge.