Another thread, OMG. Oh well.
Should you be standing or this and that. In the docs office your prob standing, in the hospital bed for IM injection you in bed so you turn over a little, or you push you but up. So a little common sense. If you can stick your glute and get it in straight into you body That's it, Hello ? this is no different from that. AS long as you can get to it.
How far in. Well as ws said, A little common sense Huh. If you 98-105 lbs. Then with a 1-1/2" you don't want to go in to hit bone, huh. If you have some meat it is 1" or 1-1/2" long for a reason and that to get the compound in and deep. So there is no mark on the needle, STICK IT IN, ALL THE WAY.
What location, look at the pics you can pull up and see. Common sense, do you remember where, or close to where you had a shot in your A$$. Now have you seen a nurse or doc measure, ever?
If you need all this info to such detail you shouldn't do this without proper supervision or an on site teacher.
With oil or water base you can use 23 x 1" or 22 x 1-1/2. With water you can use a 25 x 1', but not a 5/8" long. FYI, I have used 22, 23, 25 with both oil and water. But 23 is kinda the general practice I believe.
AGAIN THIS IS NOT ROCKET SCIENCE. ...crazy mike suggest you read more
PS OP did you not read the many, too many threads about aspirating. Common sense, hello. When has your nurse or doc ever, ever aspirated when sticking your a$$