Nope, the fender struts on the rear fender are different so the holes won't line up.
under the seat
If you are doing an oil change it would be 2.75 quarts. That will bring it to just under the full line when cold.
The proper air gap is .032 to .036 depending on spark plug brand.
you have to have the battery held up by someone or somthing to attach the cables, then when you get them tight, lift the batt up until the bottom clears the tray and then slide it back
Manual. Get one.
No.
Three
The front fenders on the wagon and the sedan are the same.
The oil drain plug on a 1999 Dyna Wide Glide is located on the bottom of the engine. It is on the right side of the engine.
Honestly, if you have to ask; take it too an experienced harley mechanic. It is very easy to ruin the carb if you do not know what you are doing? Save yourself the money of buying new parts by paying too have it done correct the first time.
In the compartment under the seat on the other side from the oil reserve
No, the rad shrouds will definitely not fit. The fenders might though.