Hovering over "Buy"... care to sanity check my thinking?!

[JAZZCNC]

Be afraid Very afraid.!!!. . . . . Nah but seriously now I wouldn't buy one unless it's purely for learning purposes and I wouldn't waste a penny trying to upgrade one. . . . Can't make Silk purse out of sows ear.!

Q1: Not seen any of the Cheaper ones come with limit switches or Home switches.
Q2: Mostly junk and the better ones are still Cheap Analog drives best avoided.
Q3: Yes and C7 is more than good enough for router. C5 or higher screws will cost more than the machine.
Q4: Best advice is don't bother only ends with you buying proper drives. You can buy Lead shine Digital drives for less than £40 on ebay and nothing you'll find or build open source will come near in performance. No point trying to re-invent the wheel
Q5: Never heard of EMC4. Thou I think you may mean Mach4. In which case No stick with Mach3 for time being and Don't go with USB it's not stable enough. Ethernet is the way to go.
Q6: Upgrade what.? if 3020 or any of the Chinese machines then Nope don't waste a penny ugrading just use and sell when learnt and ready for better.
Q7: The TB based drives are Low voltage which if pushed have habit of letting out the Magic smoke. Again just avoid them they are bad news.

To learn with the Cheap chinese machines are great Entry into CNC but don't expect the world and Don't waste money trying to make better and you'll get value for money.