You will be able to use the metal cutting blade, just do it outside because it will throw lots of sparks. Regular metal drill bits will be fine for drilling 1/8 inch angle.That and a drop or two of oil.
Then you will need to add some ingenuity to your job. Without seeing it, I would say some through bolts will hold anything to your round legs. You may need to attach to the wood first to hold parts in place.
The pipes for the clamps sometimes are sold at the box stores. If not you can get what you need at a plumbing supply store. They cut and thread...ussually.
You sound like you have it figured out, send some pics out when you finish, or need more help.
Sounds like fun, good luck.