no
the best way is to replace with a known good battery also a voltmeter - read battery under load - it should be near 9 volts
The nine volt battery is available in so many brands that it is hard to keep up anymore. I would think that the best one would be a charged one and go from there. I have never had a problem with any nine volt I've purchased, mainly because it is already one of the most expensive batteries sold.
you better not. you need a 9V regulator for this, not a resistor!
No.
no
You can buy 9V batteries from almost any supermarket
A car battery is much larger and designed to provide high amounts of power to start a car's engine, while a 9V alkaline battery is smaller and typically used in smaller electronics or devices that require less power. Additionally, car batteries are rechargeable, while 9V alkaline batteries are typically single-use and disposable.
"Stronger" isn't a good word here. Given the most common D and 9V batteries, it's more a question of "different" than "stronger". The 9V has a higher voltage, while the D cell has a bigger capacity. What'll be best depends on what you need. It's like trying to decide if a sports car is better than a tractor.
very
Current I = V/R V = 9V R = 100ohm I = 9V/100ohm = 90mA
yes the invert mini takes 1 9v battery. it is in the grip frame. you should get a 9v with the gun/