Actually, your jurisdiction may require a gas-certified technician to install the cooktop. Incorrect connection (and improper leak detection) of a gas appliance can be deadly.

I'm a seasoned DIYer, but I wouldn't DIY a gas appliance. Microwave drawers are tricky Due to the glides. My advice would be to read the installation manuals then decide if you feel up to the task.

If the wall oven were electric, it would be fairly simple with two people. Gas I would leave along. Gas is nothing to mess with.

Gas requires leak checking. Other than that its simple. And soapy water makes that part easy. Read the manuals and watch YouTube. Then come back with anything you're not clear on. You need enough help for something heavy to even bring it into your house.

Thanks for the feedback. I guess I'll get quotes for installing everything. Maybe I can get a head start on the microwave and if I mess it up, get the pro to fix it. I'll probably leave the gas work to the pro, but maybe I'll have him check my work for safety.

It's all DIY. Nothing magical about connecting gas. Just make sure you check for leaks.

I'd worry about my insurance if an accident or fire occurred. Would I be covered?

Check your warranties and make sure that none of them are altered by you DIYing it. Also, I know that some brands offer incentives to have their appliances installed by an authorized/certified installer