I have an existing 200-amp main panel with insufficient space to add the two 240-volt circuits needed for a dryer and range(these appliances are currently gas). I plan to install a 100-amp subpanel(main lug type) with neutral and ground isolated, adjacent to the main panel. I will have to relocate a 40A/240V circuit (used for the air conditioning system) from the main panel to the subpanel in order to make room for a new 100-amp breaker in the main panel to service the subpanel. The new subpanel will provide a 30A/240V circuit for the dryer, a 50A/240V circuit for the range and the relocated A/C circuit (40A/240V). The subpanel will have space for 6 additional 120V circuits for future use if needed.
The wire sizes I am planning to use are: AWG 6-3 w/grd between the main and subpanels, AWG 8-3 w/grd for the range circuit(approx 50 feet from the panel) and AWG 10-3 w/grd for the dryer(approx 50 feet from the panel). I'll reuse the existing A/C wiring. This is a home owner DIY project.
QUESTIONS: Are my wire sizes adequate? What are the specification requirements for the "main lug" subpanel? Any considerations I missed? Your reply will be appreciated.

Do not isolate the equipment ground bar, it gets bolted directly to the panel box, the neutral bar remains insulated.

Move low amp circuits or seldom used circuits to the sub, leave all large circuits in the main panel.

Your wire sizes are fine providing your appliances are typical size.

Specs for the sub? Not sure what you need, a MLO panel is one without a main breaker. A "convertible" panel usually is an MLO with an available main breaker kit purchased separately. Get the amount of circuits you need plus extra space for future, usually 10, 12, 16, and 20 circuit are found.