Have you tried all the hardware stores in your area for expanded or is home Depot the only one around you? I got an offcut from a local independant hardware store, about 48" x 9" for $15, bent it into a rough cylinder shape, then fixed it in place with 3 1/4" stainless steel bolts, nuts and washers( I do not weld). attached it to a new Weber charcoal grate for a 22.5" kettle with stainless steel cable ties, but I've seen other brethren use fencing wire. Made 3 legs from 3" long 1/4" bolts and I have a cheap pizza pan as an ash catcher(the bolt heads keep it in place).
The step bit is great for the 1/4" holes - if you can find a cheap one or borrow one, you should be fine. For my 1" intake holes I used a 1" hole saw instead of a step-bit and it worked fine.
If you're going with the flat lid with holes, plug them with wads of tin-foil at the end of the cook to choke out the fire(and close the intakes, of course).
You should use the search feature at the bottom of the page for more detailed answers. Search "No-weld UDS basket" and " If a Reckneck built an UDS".
I don't think you need a heatshield, but drill away and plug with 1/2" long SS bolts until you try it out and see if you need something.
I built mine last August and I love it. Have fun!