While you can create PUG/Scrim/Practise servers of your own, we do not enable DM server creation as it would lead to multiple DMs being created with just a few players in each. We have a 16 man FFA DM running at all times in all our locations: Bangalore, Mumbai, Singapore & HK, for you to join.
Aim_map servers are something we are planning on down the line, but other aspects take more priority at the moment. But it is something we plan to include down the line.
Coming to your last query, practice servers are launched with certain commands for teams/players to practise various things like smokes/eco executes/full buy executes etc. It is not meant for a full practice game as such.
For a normal game, you can either launch a PUG server and populate it with your teammates and/or wait for other randoms to join. OR you can click on the play icon on the app, and create your own 10 man lobby, which is a private invite only 10 man PUG server for your teammates/friends to play in exclusively with no randoms joining.
Hope this helps.