It depends on the battery used. Older batteries batteries, like Cadmium, will be relatively heavy, while 9V alkali batteries today weigh about 100g and 9V lithium batteries weigh about a 3rd of that at 33,8g
eletrical neutrons
No
it will be too much of a jump. i would recconmend a 2s (7.4V) lipo battery
No, the battery will be overcharged and battery damage will occur if it is done.
No, a lead acid battery is a wet cell battery and a 9 volt alkaline battery is a dry cell battery.
It heats up very hot and may explode.
Sure. But not much water, a 9 volt battery has very little power (energy).
no
A 9 volt battery is stronger than a 1.5 volt battery because it has a higher voltage. The higher voltage allows the 9 volt battery to power more demanding devices and last longer than a 1.5 volt battery.
1.3cm
a 9 volt battery
buy a battery charger