You're doing great.
1. Jup, you can apply for the job before, within or after your time as a conscriptor. Being not taken as a wannabe officer does not excludes you from performing military service or a civil service.
2. Right.
3. After the 3 month of basic training (infantry) you start with your special training (for example doing gunnery and driving training in a tank unit or learning radio operations in a EW unit). After this you start your officer courses. For example in my unit there were future officers with the rank of Gefreiter OA (OA stands for future officer) doing the same things like normal Gefreite for some time (Despite some extra training and service for them after the normal duty).
After this you have your officers courses on various training facilities with some phases of practical training (For example as a group leader or tank commander) in the normal units.
This lasts till month 15.
From then on you start at one of the two Bundeswehr-Universities (Or you might do an exchange program, for example with France).
The kind of study often enough has nothing to do with your military branch and is mainly for your life after the Bundeswehr.
This lasts till month 54.
After this you enter full service again till you leave after 12 years or you go on serving after these years.
The difference between now and the past not long ago is that basic training is now done in one of our training btls and special training for your branche starts later (After some general officer courses and not before them) and is also seperated from the normal units.
This results in the officer still starting as a normal green soldier but being seperated from their "normal" comrades and first seeing a real unit during their practicing phases as groub leaders/tank commanders/etc..
For me this is wrong because of two things.
The wannabe officers have no idea of a real unit and how you feel at being just one of hundreds. And suddenly they have to command a group. Not a very good mixture.
And they are having less time in a unit of their branch of service which results in officers having less ideas of for example having to run a group or tank in a maneuver than before.